CH20_Electric+Circuits

Part One: Electric Circuits toc

1.
what makes a bulb light?

In order to make a bulb light, a circuit must connect a power source (battery) to the light bulb and back to the power source. Two wires must connect the + side of the battery to one end of the light bulb and the - side of the battery to the other side of the light bulb.

Components: A light bulb, two alligator clamps, and 1 battery.

2. what will happen to the bulbs when you disconnect a wire from one of the points in the photo?

__Hypothesis:__ At any of the points, a wire that is disconnected will cause the lights to go out. This is because the circuit is no longer complete.

__Data:__ These are the results of when the wire is disconnected from the corresponding point in the picture above. __Conclusion:__ Based on the results we can see that the lights go out, we know that the light does not get the electron flow needed for th e bulb to light. This is because the circuit is no longer closed and does not allow electrons to flow. Because of this the electrons stop moving and the bulb does not light.
 * A || No light ||
 * B || No light ||
 * C || No light ||
 * D || No light ||
 * E || No light ||
 * F || No light ||

3. What type of object, when inserted into the space labeled “something” in the loop shown below, will allow the bulbs to light?



__Hypothesis:__ From where it lies in the picture, the something necessary in between the two light bulbs must be a conductor in order for the bulbs to light. This is because only a conductor will allow electrons to flow across the surface and complet e the circuit. With an insulator the electrons would stop their electron flow, causing the bulbs to not light.

__Data:__ In order to test this circuit, I placed a variety of objects in the circuit where the "something" is in the picture above. __Conclusion:__ Based on my results we can see that my hypothesis is correct, and that in order for the bulbs to light the 'something' must be a conductor. The conductor allows the electrons to flow across the surface of the object and completes the circuit.
 * Object || Light? || Circuit ||
 * paper clip || yes || [[image:Paper_Clip.jpg width="211" height="160"]] ||
 * copper ring || yes || [[image:Ring.jpg width="218" height="164"]] ||
 * string || no || [[image:String.jpg width="209" height="158"]] ||
 * cardboard || no || [[image:Cardboard.jpg width="210" height="158"]] ||

4. What is a conductor and what is an insulator? How do you know? How can you test this using our loop configuration?

A conductor is an object that allows the flow of electrons along the surface of the objects. In this experiment for number 3, the paper clip and the copper ring are conductors. An insulator, on the other hand, is an object that does not allow the flow of electrons on it's surface. In this experiment for number 3, the string and cardboard are insulators. It is possible to test for conductors and insulators using our loop configuration by placing the object in the circuit where the image says "something" in the circuit. If the bulbs light when the circuit is complete, then that is an indicator that the object is a conductor. If the bulbs do not light when the circuit is complete then that is an indicator of an insulator.

5.
What parts of a socket and bulb are conductors and which are insulators? What is the conducting path through the bulb?



__Hypothesis:__ From the socket, I believe that the two metal clips are conductive, while the plastic base is an insulator. On the light bulb, I believe that the threaded section and tip are conductors, while the glass and black ring are insulators.

__Data:__


 * Bulb**
 * Yellow Wire (- side of battery) || Green Wire (+ side of battery) || Light? || Setup ||
 * Threaded Section || Tip || Yes || [[image:Photo_on_2011-10-16_at_12.28.jpg width="214" height="161"]] ||
 * Threaded Section || Black Ring || No || [[image:Photo_on_2011-10-16_at_12.28_#2.jpg width="226" height="171"]] ||
 * Threaded Section || Glass || No || [[image:Photo_on_2011-10-16_at_12.28_#3.jpg width="225" height="170"]] ||
 * Socket**
 * Yellow wire (- side of battery) || Green Wire (+ side of battery) || Light? || Setup ||
 * Clip || Clip || Yes || [[image:Photo_on_2011-10-16_at_13.10.jpg width="223" height="169"]] ||
 * Clip || Plate || Yes || [[image:Photo_on_2011-10-16_at_13.11.jpg width="233" height="175"]] ||
 * Clip || Base || No || [[image:Photo_on_2011-10-16_at_13.11_#2.jpg width="234" height="179"]] ||

__Conclusion:__ Based on the results of the first experiment with the threaded section and the tip, I discovered that they are both conductors because they completed the circuit and caused the bulb to light. Because I know this, I can test for the other parts of the light using this knowledge. Because I know that the threaded section is a conductor, I placed one wire on that and the other wire on the black ring. When that did not create light in the bulb, I knew that the black ring is an insulator. I repeated this process with the glass and got the same result, meaning that the glass is also an insulator. For the socket I used the same process, starting with a circuit where the wires connect to the two metal clips. The bulb lit, and therefor I could conclude that both of the clips are conductive. Then I tested the metal plate by removing the green wire from the clip and placing it on the proper plate. When the bulb lit, I was able to conclude that the metal plate is also conductive. Then I removed the green wire from the plate and placed it on the blue base. Because the bulb did not light I can conclude that the base is not conductive.

The conductive path of the light bulb can be seen as a green line in this photo:

6. Practice Set: The CCP

__Will these light bulbs light?__ __In the Tip, out the Side or Out the Tip, in the Side__

7. How can you light a bulb using one battery, one bulb, and one wire ONLY? How many different correct ways can you do this? What DIDN’T work, and why?

__Hypothesis:__ By touching the tip of the light bulb to the (+) end of the battery and having a wire connect the (-) end of the battery to the threaded section, it is possible to light a bulb with just one battery, one wire, and one bulb.

__Data:__ Four working methods

Threaded Section touching (+) Threaded Section touching (-) Tip touching (+) Wire connecting tip to (-) Wire connecting tip to (+) Wire connecting threaded section to (-)

Tip touching (-) Wire connecting threaded section to (+) __Conclusion:__ While my hypothesis was correct, there were three more methods of creating a complete circuit. Through trial and error, I found that there are certain requirements for this to be a successful circuit. First, the bulb must be touching one end of the battery with either the tip or the threaded section. Second, a wire must be touching the opposite end of the battery. Third, the wire must be touching the conducting end of the bulb (tip or threaded section) that the battery is not touching.

8. Practice set: Basic Circuits





9. What is a circuit?

A circuit is a complete loop of conductors in which charges can flow. A circuit requires a complete loop of conductors with no gaps or insulators, as well as a power source to make the electrons flow.

10.
What does a compass tell you about what is happening in the wires of the circuit? __Hypothesis:__ A compass needle will be attracted to the charge of the circuit and point towards it. It indicates that there is an electron flow in the wires.

__Data:__

media type="file" key="Movie on 2011-10-17 at 00.48.mov" width="300" height="300"

__Hypothesis:__ Based on the data above, it can be clearly seen that the compass needle moves when the circuit is completed. This is a clear indicator of a complete circuit, as well as that the compass needle is affected by the electron flow of nearby circuits.

11. What effect does reversing the battery pack have on the compass deflection? What does this mean about the role of the battery in the circuit?

__Data:__ media type="file" key="Movie on 2011-10-17 at 00.55.mov" width="300" height="300"media type="file" key="Movie on 2011-10-17 at 00.51.mov" width="300" height="300"

By using the same experiment as in number 10, we are able to test the results of reversing the direction of the battery pack. Through trials, we are able to see that the reversal of the battery pack causes the direction in which the compass needle moves to switch as well. This is a clear indicator that the direction of the electron flow has reversed in this circuit. As a result, we can conclude that the affect of the battery is to directly control the electron flow in a circuit and forces the electrons to move.

12. Practice Set: Wires
 * 1) [[image:Photo_on_2011-10-17_at_01.09.jpg width="475" height="359"]]
 * 2) Explain why you believe your answer to question #1 is correct. Be sure to use the words "insulator" and "conductor" as part of your explanation.
 * Through previous experiments we have proven that a paper clip is a conductor. This means that it allows electrons to flow along the surface and creating a complete circuit. Conductors, rather than insulators, are known to allow electrons to flow with very little resistance, and as a result it does not matter where the paper clip is relative to the bulbs, they will be as bright as one another.
 * 1) Write in your own words the definition of __circuit__which anyone could use to determine if a given set of connections is or is not a circuit.
 * A circuit is a complete loop of conductors in which charges can flow. A circuit requires a complete loop of conductors with no gaps or insulators, as well as a power source to make the electrons flow.
 * 1) We have observed in several activities that as soon as a very small gap is produced anywhere in the circuit, the bulbs go out. Would you classify air as a conductor or an insulator?
 * When there is a gap between wires in a circuit the bulbs go out. This is a clear sign that it is no longer a complete circuit with air in between the conductors. As a result, air must be an insulator.
 * 1) Indicate whether each of the following are true or false and state evidence of why.
 * Charge moves out of each end of the battery into the loop **False**
 * When testing with the compass, we tested the deflection in the wires of a circuit by moving the circuit over the compass. At each point in the circuit they deflected in the same direction at every location for the circuit, this indicates that the electron flow is in the same direction.
 * Light bulbs are non-directional devices (they work even if you turn them around). **True**
 * Through several trials with the compass we have reversed the directions of the batteries and the bulbs have lit each time. This is a clear indication that the bulbs are non-directional.
 * The battery determines the direction of the electron flow in a circuit. **True**
 * When testing with the compass, we noticed that when the battery pack is reversed, the direction the needle moves is reversed. This is a clear indication that the battery directly affects the direction of the electron flow in a circuit.
 * A compass can be used to determine the exact direction that charge flows in a circuit. **False**
 * Based on our previous experiments we noticed that a compass moves based on the direction of electron flow in a nearby circuit. We can not, however, use this to determine the direction that a charge flows, just to know when that direction is reversed or not.
 * Metal substances are generally conductors. **True**
 * We have proven through trials that paper clips and copper rings are conductors. Both of these items are metal and when either of them are placed in a circuit with a bulb, the bulb will light.

13. What is a Genecon and how does it work? What does it tell you about the role of the battery in the circuit and why?

__Hypothesis:__ A Genecon is a rotating handle attached to a motor. This motor can be powered by a battery to rotate the handle. It can also be used in a circuit to light a bulb. The motor can convert mechanical energy into electrical energy (light a bulb) or convert electrical energy into mechanical (turn the handle). __Data:__ Because I was not able to take home a Genecon with me, I wrote down my observations as drawings.

__Conclusion:__ Based on my results from the circuits created, we know that the Genecon can generate electric energy or exert it depending on the circuit. We know this because the motor attached to the handle can use electric energy from a battery to rotate the handle as well as be used to light a bulb. This tells us that the battery in a circuit acts as a power supply in that it powers the electron current to flow and follow the circuit. When we used the Genecon to power the bulb, it was supplying the force necessary to make the electrons flow in the circuit, similar to how a battery does.

14. Readings: [|SchematicDiagrams] and @http://www.physicsclassroom.com/Class/circuits/u9l4a.cfm.

15.
What is a schematic diagram? What are the symbols for the various circuit elements?

A schematic diagram is a picture of a circuit in which a viewer can follow the electron flow. The objects included in a schematic diagram are represented as simple images that allow a viewer to identify what the object is as well as what the charges are of each portion or which direction the electrons are flowing in the complete circuit. The symbols for the various circuit elements



16. Practice Set: [|Schematics] 1. 2. If bulb B is removed from the socket then the circuit is no longer complete. As a result, bulb A goes out. In order for this circuit to be complete the clips on socket B must be touching, or they must have a conductor connecting them.

3. Based on the work done in this unit, the light bulbs, wires, and clips are all objects that are conductors and allow electrons to flow. The air in this is an insulator and this can be seen when bulb 2 is removed and the circuit is no longer complete. The air in between the two clips acts as an insulator, stopping the el ectrons from flowing to bulb C.

4. Explanation: This diagram above could be used as a set up to test whether an object is an insulator or a conductor by determining whether the bulb lights or not. We know that a conductor allows the flow of electrons to complete a circuit, causing light, while an insulator does not allow electron flo w and makes the circuit incomplete. If we want to test an object we can do so by placing the object in the circuit where it says "something" on the circuit. If the bulb lights with that something in the circuit then it is a conductor, but if the bulb does not light then it is an insulator.

5

6. 17. Readings: [|Capacitance]

18. What is a capacitor and how is it made?

A capacitor is an object which allows a circuit to remain a short period of time with an active power supply, as one side of it 'charges' with electrons. Inside of the electrons are two metallic objects separated by a weak insulating object in the middle. When the electrons flow, they travel into one side of the capacitor and electrons, from the electric fields, are forced out of the other end of the capacitor, completing the loop. This only lasts until the capacitor's charging side is filled, in which case the electrons can not flow and the circuit is not complete. The capacitor is charged, and can only be released if the capacitor is made the power supply of a circuit (removing the batteries from the circuit), in which case the bulbs light until the charged capacitor is completely discharged.

19. What is the effect of a capacitor on a closed loop?

A capacitor allows a closed loop to have an electron flow as long as it is charging, or as long as it is discharging, in the circuit. These processes allow electrons to flow throughout the circuit including the capacitor. When the capacitor is charged or discharges, however, the bulbs go out and the circuit is no longer complete. This is because either the capacitor is charged and will not force more electrons through the circuit, or that the capacitor is balanced and there is no longer an electric field to force the electron flow within the circuit and the capacitor.

20.
What is origin of mobile charge? From where does the mobile charge originate during the charging and discharging process?

Origin of mobile of mobile charge is the creation of electron flow along the circuit. This mobile charge originates from everything conducting in the circuit and is caused by a force from a power supply (battery or capacitor).

21. Practice Set: [|ElectricalEnergy]


 * 1) Yes the bulbs will light in figure two. This is because the relative position of a light in a complete circuit with a capacitor and battery is irrelevant. As long as the light bulbs are a part of the circuit and the circuit is complete, the bulbs will light.
 * 2) A capacitor can be charged using a battery, bulbs, wires, and a capacitor by creating a circuit which uses wires to connect the ends of the battery to the ends of the capacitor. It is important that each wire is attached to a separate end of the battery, and connect to a separate end of the capacitor. A light bulb can be included in this circuit at any point by additional wires, and lights when the capacitor is being charged. Once the capacitor is charged, however, the bulb will go out.
 * 3) To discharge a capacitor you must remove the battery from the circuit. It is important that the capacitor is the power supply of this circuit. It is also important that wires connect one end of the capacitor to the other. A light bulb can be placed at any point in the circuit with additional wires and would be used as an indicator of discharging. When the capacitor is discharging the bulb will light but when the capacitor is finished discharging the bulb will go out.
 * 4) In order to test if a capacitor is charged WITHOUT discharging it, it is important to put the capacitor in a circuit with a battery, as well as a light bulb. This can be done by using wires to complete the circuit. If the capacitor was initially charged, then the bulb will not light and the circuit will not be complete. If the battery was not completely charged, however, the bulb will light indicating that the circuit is complete and the capacitor is charging.
 * 5) A) Incorrect B) The circuit for #5 is incorrect because the arrows show charge flowing out of BOTH ends of the battery. This is not possible, as the electrons will only flow out of the positive end of the battery.
 * 6) A) Incorrect B) The circuit for #6 is incorrect because the arrows show charge flowing out of BOTH ends of the charged capacitor. This is not possible, as the electrons will only flow out of the positive end of the capacitor.
 * 7) A) Incorrect B) The circuit for #7 is correct because the arrows show charge flowing across the capacitor and stopping at the battery. This can be seen as a gap in front of the battery.
 * 8) A) Correct B) The circuit for #8 is correct because the arrows show charge flowing out of one end of the capacitor. The electrons will only flow out of the positive end of the capacitor to the negative.

22. Make a Model: [|AirCapacitor]

23. Investigating the [|Air Capacitor]



24. Practice Set: [|Capacitance]


 * 1) When air is blown into one side of the capacitor it does not come out of the other when the other end is closed. This is because there is no way for the air to get out of the capacitor. Instead the increase in pressure on the near side causes the air in the far side to compress and make up a smaller area of space. When the middle divider moves towards the far side it is compressing the air particles of the far side and is making it concentrated. When the far end is open, however, the air does leave the far end because it is forced out by an increase in pressure from the divider.
 * 2) An air capacitor is neutralized when the divider is directly in the middle of the two ends of the capacitor. When there is an equal amount of force on each end of the divided they exert an equal amount of pressure on the divider, causing it to stay in the middle. If it is not neutralized the divider is closer to one end than the other.
 * 3) The amount of air pressure within that side of the capacitor increases causing more pressure to be exerted on the divider. The divider, as a result, moves towards the far side where the air is trapped until the pressure of each side are equal.
 * 4) When air is drawn out of one side the air pressures are unequal and the divider moves towards the side where the air is drawn out. This is because the air pressure on that side decreases.
 * 5) Both the membrane and the insulating layer both respond to forces in their environments. The membrane responds to the change in air pressure while the layer responds to the change in electric forces within the capacitor.
 * 6) The membrane in the air capacitor is much larger than the insulator in the circuit capacitor. The membrane is also more flexible than the insulator, and as a result bends physically to the air pressure. The insulator, on the other hand, does not bend to the electric force, but the force still affects the electrons within the capacitor.
 * 7) [[image:Photo_on_2011-10-17_at_13.41.jpg width="445" height="335"]]

=Part two: Resistance=

1.
What effect does the type of bulb have on a capacitor during charging and discharging?

__Hypothesis:__ The type of bulb in a circuit charging a capacitor will affect how long and how bright the light is while charging. The bulb will also affect how long it takes the capacitor to charge/discharge because of the different levels of resistance caused by each type of bulb.

__Data:__ In order to test the effects, we create a circuit that tests the charge/discharge of the capacitor with round bulbs, long bulbs, and a Genecon. The charging and discharging times would be the same, so it does not matter whether the circuit tested is for when the capacitor is discharging or charging.

Round bulbs (charging) media type="file" key="Movie on 2011-10-20 at 21.33

Long Bulbs (discharging)

media type="file" key="Movie on 2011-10-20 at 21.38.mov" width="300" height="300"

Genecon (discharging) media type="file" key="Movie on 2011-10-20 at 21.40.mov" width="300" height="300"

__Conclusion:__ Based on the test circuits used for a capacitor, we can see that there is a clear difference in light for the long bulbs versus the round bulbs and even the Genecon. The long bulbs shined brighter and for longer than the round bulbs, and the genecon handle rotated for only a short time. The difference between the round and the long bulbs is that the round bulbs have less resistance, so the charge flowing through it flows for a shorter time and does not create as much friction against the filament than the round bulb.

2. What are the differences between the filaments of round and long bulbs? (Use a microscope.)

__Hypothesis:__ The filaments of round bulbs will be shorter, as well as thicker, than the filaments of the long bulb. This is because the round bulb is smaller, and brighter. A thicker filament would cause the bulb to be brighter yet the glass area of the bulb is smaller. Because they have the same function, I believe that the filaments will be identical in every other way.

__Data:__ Observations were found when looking at each bulb under a microscope.

__Conclusion:__ Based on what was seen in the microscope, it is clear that the short bulb's filament is thicker and shorter than the long bulb's filament. This explains why a round bulb is brighter, even though it is smaller, when under the same charge. Because the filament is thicker on the round bulb, it has less resistance on the current flow, and more electrons can move across the filament at once. Because the long bulb's filament is thinner, it has more resistance to electron flow and less electrons flow through the circuit, causing the bulb to be dimmer.

3. How is air moving through straws analogous to charge moving through a filament?

When blowing air through straws, it can be seen that it is easier to blow air through a thicker straw than a thinner straw. This is similar to how the round bulb, with its' thicker filament, is brighter than a long bulb. When the air tries to get through the straw, there is resistance by the straw to how many air particles can make it through, and this is determined by the straw and how thick it is. The thicker the straw, the more air can pass through at once. With the current moving through a filament, the current has the exact same relationship as the air had going through the straw. There is resistance in the current by the filament, and how thick it is. The thicker the filament, the more current can pass through at once, and the brighter the light.

4. What is the difference between flow rate and flow speed?

Flow rate is the amount of charge that flows through a point at any interval of time. If a wire in a circuit is very wide and allows 100 charges to flow alongside one another, then it has a high flow rate. If the wire is narrow and only allows a few charges to flow alongside one another, then it has a low flow rate. It is important to note that flow rate has nothing to do with flow speed. The flow speed, which is completely different, is the velocity in which a charge moves along the circuit. It does not matter what the flow rate is, the flow speed is simply how fast the current is moving through the current.

5.
How does the number of bulbs in a single loop affect the overall current and resistance in a circuit? __Hypothesis:__ The number of bulbs in a single loop will not affect the overall current and resistance in a circuit, because the bulbs all have the same amount of resistance on the charge flow. The current, therefore, will remain the same and unaffected by the amount of bulbs in the circuit.

__Data:__ 1 Bulb media type="file" key="Movie on 2011-10-20 at 21.58 2 Bulb media type="file" key="Movie on 2011-10-20 at 22.07.mov" width="300" height="300" 4 Bulb media type="file" key="Movie on 2011-10-20 at 22.10.mov" width="300" height="300"

__Conclusion:__ Based on the data above, it is clear that the amount of bulbs have no effect on the charge and the charge flow within the circuit. This can be seen in the compass needle of every trial. The needle, regardless of how many bulbs, bends the same way and to the same degree as the other trials. This indicates that the current flow is the same direction and magnitude each time. The only difference in these circuits is that the bulbs are not as bright, and this is because each bulb uses some of the energy from the current. Each bulb has the same amount of resistance and therefore allows the same flow rate in the circuit. Because of this the flow rate is not affected by how many bulbs there are.

6. Problem Set: [|Resistance]



2. No. This can be tested by charging a capacitor with round bulbs and then discharging it round bulbs; then by comparing the result to when the capacitor is initially charged by long bulbs and then discharged by round bulbs. Regardless of which bulb is used to charge the capacitor, the discharge with round bulbs appears the same, indicating that there is the same amount of charge stored each time.

3. Charge the capacitor with round bulbs, then discharge it with bulbs of Brand X. Compare the brightness and length of time lit to the long bulbs and the round bulbs when discharging. If Brand X is brighter and shines for longer than the other bulbs, then it is more resistant to current flow, causing the charge to flow for a longer duration of time. If Brand X lights more dimly and for a shorter duration of time, then it is less resistant to current flow and allows more current to flow through at a time.



7. Read and Summarize Lesson 3 Method 2B: @http://www.physicsclassroom.com/Class/circuits/

1. What (specifically) did you read that you understand well? Describe at least 2 items fully.
 * The path of an electron does not follow a straight line, but rather is a zigzag pattern. The electron is 'pushed' in the right direction by the current flow which forces the current to flow in one direction. This current flow is created by a power supply (battery pack) and moves the current along the circuit. Although it is not in a straight line, the electron moves in the right direction and therefore flows in the current.


 * Resistance is the interference of current flow caused by an object within a circuit. It slows down the flow of charge and resists the flow of the current. The resistance is dependent on what type of object it is, how conductive it is, and how much current flow it allows at any time. Resistance could be decreased by replacing the substance with something more conductive or something thicker which gives room for more current.

2. What (specifically) did you read that made you feel little confused/unclear/shaky, but further reading helped to clarify? Describe the misconception(s) you were having as well as your new understanding. > 3. What (specifically) did you read that you don’t understand? Please word these in the form of questions.
 * Because I was knew to it, I was unsure about the concept of Ohm's law and the equation ∆v = I * R. As I kept reading they clarified the idea that the electric potential difference between two points on a circuit is equal to the product of the current between those two pointsand the resistance of all objects between those two points. The page also went on to say how the equation could be rearranged to become I = ∆v/R, which makes it easier to solve for current when we know the electric potential and the resistance between the two points.
 * I had trouble understanding the page on power. It was not very descriptive about the introduction of power, and each equation only had one or two sentences to describe each equation. When do I use each equation, and what is the difference between the two? It simply looks as though they plugged in one variable for another, and I am confused as to how that helps with anything.

4. What (specifically) did you read that you thought was pretty interesting, that you didn't know before, or can easily apply to your every day life?
 * I found it interesting that objects in series in a circuit will have less and less power along the circuit to use. The amount of energy flowing in the circuit is partly used up by each bulb in the circuit. This definitely applies to other electrons other than just light bulbs. If I create circuits or have any circuits of electronics (Tv, computer, etc.) I will be sure to try to avoid using a series, as some of the devices would not get a lot of power for charging.

8. Reading and Questions: [|Pressure Difference]

> > The first argument compared electric pressure in a capacitor to the pressure of water, saying that when the capacitor is full of charge then no more charge can fit inside and therefore is charged. > > > The second argument compares electric pressure to air pressure, saying that more electrons can be fit in the capacitor if more force is added. The pressure of the electric charge will increase as more charge is forced into the capacitor, same as how air reacts to an increase in force that would cause it to be overcrowded in a space. They both would have a pressure to release the excess particles and would increase in pressure until it equaled the force being exerted on it. > > Based on what I have learned from the reading, the second argument is more accurate in describing the charging and discharging of capacitors. The first argument can be proven wrong by creating a circuit to charge the capacitor, and after it is charged add another battery to the circuit. The capacitor will gain additional charge even though it had been charged before. This disproves that the charge, like water, fills the space and no more can be added to it. Like air, the additional charges were fit into the capacitor by increasing the force exerted by the power supply. This caused more particles to fit within the already charged capacitor plate, similar to how air can be pressed into a smaller place by force, creating room for additional air.
 * 1) Write a sentence summarizing the points of the first argument. Use your own words.
 * 1) Write a sentence summarizing the points of the second argument. Use your own words.
 * 1) Based on your understanding of the reading, which argument is the closest fit to the behavior observed in actual circuits?

4. In terms of electric pressure, how does charge "know" which direction to move?

Charge “knows” which direction to move because the battery pushes the current inside of it in that direction. This creates a domino effect of charges being pushed in that direction, with the charge on the opposite end of the battery being forced to the beginning of the external circuit. The charge knows which direction to move because it is pushed in that direction

During the charging process there comes a time when the bulbs no longer light. Does this mean that the battery has stopped pumping charge? Explain your thinking.

When the bulbs no longer light, this indicates that the electron flow has stopped. This is because the capacitor is charged, and can no longer force charge out of the lower plate in an electron flow. This means that the battery has stopped pumping charge because the circuit is no longer complete, and therefore the charge has nowhere to flow.

What is the technical term for Electric Pressure?

The technical term for Electric Pressure is Voltage.

5. A) How does charge "know' when to stop moving?

Charge “knows” when to stop moving because there is no place for it to move to. Similar to a traffic jam on a highway, once the first car has no place to move in front then it stops, and the cars (charges) behind have to stop. This causes all charge flow to stop completely.

B) How does this idea explain the inability of a "dead" battery to run a portable CD player?

The explanation of part A can be used to explain why a ‘dead’ battery cannot run a portable CD player. When a battery is dead, this means that is does not have the energy to move the charges from the end of the circuit with low electrical potential to the end of the battery where there is high electrical potential. As a result the charge cannot flow to the other side of the battery and stops charge flow like the “traffic jam” I explained in part A. As a result the charges stop moving, and power does not flow through the CD player, causing it to not run successfully.

9. Notes/Activity: [|Color Coding]

__Step A:__ Because of the large difference in electric pressure, a lot of current will flow across the bulbs. The battery will push unopposed with a lot of force, and as a result the bulbs will shine very brightly.

__Step B:__ Because it has been charging, the capacitor going to resist the push of the battery, but there will still be a flow charge of current towards the capacitor. As a result the bulbs will light, but not quite as bright as they had initially.

__Step C:__ At this point the capacitor is almost completely charged, which means that it almost has as much electric pressure as the battery is exerting. As a result the current flow is slower, and the bulb at this point is dim, but there is still a flow of charge and the bulbs are lit.

__Step D:__ By now the capacitor is completely charged, and has as much electric pressure as the battery. The current flow has slowed down to a stop and the bulbs are no longer lit. This is a clear sign that the capacitor is charged.




 * 1) [[image:Photo_on_2011-10-21_at_00.05.jpg width="431" height="324"]][[image:Photo_on_2011-10-21_at_00.05_#2.jpg width="380" height="286"]]
 * 2) Figure 4B because when a cable initially connects to a circuit between the two bulbs it has a neutral charge and the cables contacting the capacitor have not been discharged, making them as charged as possible.
 * 3) 4B because the flow rate is caused by the pressure difference across the bulbs. As a result, the figure with the greatest difference in electric pressure has the greatest flow rate.
 * 4) The bulbs dim in figure 4C because the capacitor, at this point, has discharged a lot, reducing its' difference in electric pressure along the bulbs. This decrease lowers the flow rate and causes the bulbs to dim.

10.
Practice Set: [|Color Coding]



11. How does the number of bulbs side-by-side affect the overall current and resistance in a circuit?

__Hypothesis:__ The number of bulbs has no affect on the overall resistance in a circuit, and therefore no affect on the flow rate, but the bulbs will become less lit as more bulbs are added. The current will become weaker as the bulbs use more energy.

__Data:__ To test this, I created a circuit with three batteries and tested two, three, and then four bulbs in a row on that circuit.

__Conclusion:__ Based on the test trials, it can be seen that the bulbs, no matter how many, are all the same brightness. The needle of the compass was used to test the current flow of each circuit. The batteries were never changed, and the compass indicated the same flow direction, but there is a noticeable increase in the degree that the needle moves with each bulb added. This indicates that there is an increase in the flow rate of the circuit as more bulbs are added, and also means that the amount of resistance in the circuit decreases. This is because there are more possible ways for the current to travel, allowing more current to flow at once, which is the definition of current flow.
 * Two Bulbs:**
 * Three Bulbs:**
 * Four Bulbs:**

12. Does adding wires in series or in parallel effect the overall resistance of the circuit? __Hypothesis:__ Because it has no resistance, adding a wire to a circuit will have no affect to the overall resistance of a circuit.

__Data:__


 * Short Circuit (caused by red wire):**

__Conclusion:__ Adding wires in series does not affect the overall resistance in a circuit because it does not change anything in the circuit. Adding the wire in series makes the circuit longer, but a wire has no resistance and the resistance of a single series circuit is determined by the most resistant object. By adding a wire into the series, there is no additional resistance. If a wire is added parallel to the circuit, however, this causes the current to be able to take multiple paths, allowing the current to flow faster. This increase in current flow is an indicator of reduced resistance. This is because with a parallel series in the circuit, more current can flow through the circuit at one time, which means less resistance. In the case above, the wire causes the circuit to skip a bulb in what is known as a short circuit, causing the circuit to flow much faster.

13. What effect do dueling battery packs have on bulb lighting and flow rate?



__Hypothesis:__ Dueling battery packs will have resistance in a series, but when parallel there is no effect. This is because the current will flow where there is less electric potential, and because the opposing battery pack is flowing in the opposite direction, the current is going to avoid the battery by taking the parallel series.

__Data:__

in the circuit, bulbs light as normal for 3 batteries || Some noticeable resistance from the single battery cell. The lights are less brightly lit than in Circuit A. || The bulbs are dimly lit, with a lot of resistance coming from the two cell battery pack going opposite to the three cell pack. || There is no noticeable light coming from the bulbs, and the opposing 3-cell battery packs are equal, causing there to be no light. || Same as Circuit C, except the current is flowing in the opposite direction. ||
 * Circuit A || Circuit B || Circuit C || Circuit D || Circuit E ||
 * No dueling or resistance

except the flow is in the opposite direction. || The bulbs are much brighter than in Circuit F, without the resistance of the left side battery pack there is more light from the bulbs. ||
 * Circuit F || Circuit G ||
 * Same as Circuit A

__Conclusion:__ Based on the data, it can be determined that opposing battery packs create resistance and interfere with the circuit. When an opposing battery is in the series of the circuit it will have a direct affect in weakening the bulbs, which is an indicator of resistance. When the opposing battery pack is equal to the original battery pack, the bulbs go out completely, indicating that there is no charge flow. When the battery pack is parallel to the series, and not directly in the series, there will be no noticeable affect because the current will avoid the high pressure end of the battery and will not be attracted to the low pressure end.

14. Practice Set: [|Battery Structure]



1. Based on your color coding, what happens to the flow rate in the circuit as the battery 'ages' due to continued use?
 * The flow rate in the circuit decreases in the circuit as the battery 'ages'. This is because the batteries create a greater amount of resistance in the circuit, causing the flow rate to slow down.

2. In terms of properties of the battery discussed in the previous reading, why do batteries 'die'?
 * According to the reading, batteries 'die' because they experience a chemical reaction that creates energy and new chemicals, and the battery runs out of chemicals for the reaction that generates energy. When this happens the energy has been released and most of what is left in the battery are the products of the reaction. Because these new chemicals can not react with one another to release energy the battery has no more energy and is considered 'dead'. The battery can be recharged by using energy to reverse this reaction, creating the initial chemicals when the battery was new.

15.
How does mixing bulbs in series affect flow rate and pressure in each part of the circuit? __Hypothesis:__ mixing bulbs in series causes the flow rate to flow at the rate allowed by the more resistant bulb. In this case the long bulb determines the flow rate based upon its resistance because it is more resistant than the round bulb. Because the resistances are different, the long bulb will have a greater pressure difference than the round bulb.

__Data:__ media type="file" key="Movie on 2011-10-25 at 13.19.mov" width="300" height="300" **Note: My arm is blocking the round bulb.**

__Conclusion:__ Mixing bulbs in a series causes a change in the flow rate and resistance on the circuit, as well as the electric pressure in each part of the circuit. This is because the flow rate of a circuit is directly dependent to the resistance of the most resistant object in the circuit. When charge flows in this circuit, it is slowed down by the long bulb which has higher resistance. As a result the entire circuit flows at the rate of the long bulb, causing the less resistant round bulb to become extremely dim, even though the same current is flowing through it as the long bulb. In the circuit above, the capacitor short circuits the long bulb while it is charging. This is because the capacitor has less resistance, causing the current to flow in it's direction. The round bulb is brightly lit and the long bulb is not lit at all. As the capacitor becomes more charged, however, it has a greater resistance, causing the current to flow through the long bulb, and the long bulb gets brighter. This adds resistance to the current flow, causing the round bulb to start to dim. By the point when the capacitor is charged it is very resistant to the current, and the current flows entirely through the long bulb, causing it to be bright, and the round bulb to be dim.

16. Reading: [|Mixing Bulbs]

1. Take a standard soda straw and cut it to the same length as a coffee-stirrer straw. Put each in your mouth and blow. Use your hands to feel the flow rate through each straw. Which straw has the greater flow rate of air passing through it? Compare the pressure difference across each straw. Which straw has the greater resistance to the flow of air?
 * The coffee straw has more resistance to air. This can be felt by my hand in this experiment because the coffee stirrer has less air coming out of it than the soda straw. The coffee stirrer resists the flow of air, and therefore less air flows through it. This is because the coffee stirrer is much narrower than the soda straw, thus increasing the air resistance.

2. If you want to increase the flow rate of air through a coffee stirrer straw, what must you do?
 * To increase the flow rate of air through a coffee stirrer we must cut the coffee stirrer shorter, causing it to take less time for the air to flow through.

3. If a long bulb has the same flow rate going through it as a round bulb, what can you say about the relative electric pressure difference across each bulb?
 * With greater resistance, the long bulb will have a greater electric pressure than the round bulb when the same flow rate goes through it. This is because the long bulb does not allow current to flow across it as easily as the round bulb, and therefore needs a greater amount of pressure to force the current through.

4. Tape a coffee straw and a soda straw together end to end. Try discharging your lungs through the two straws connected in series. How long does it take compared to either the coffee straw or the soda straw alone?
 * This process of blowing through both straws in series is harder than with just the coffee or soda straw. It takes longer for the air to flow through.

5. Does the order of the straws (coffee to soda or soda to coffee) make a difference in the amount of time it takes to discharge your lungs?
 * The order of the straws DOES NOT MATTER. It is the same length of time when blowing through the straws in either order.

6. In the circuit below, the positions of the round and long bulb have been reversed from Activity 2.

a) Color code the two circuits. Include bulb rays and arrow tails.



b) Predict what you would see during the transient phase if the large silver capacitor were placed in parallel with the long bulb before the final connection was made.

If a large silver capacitor were placed in parallel to the long bulb before the circuit was completed, the capacitor would short circuit the bulb. The long bulb would not light at first and the round bulb would be very bright. As the capacitor charges, however, the current will begin to flow through the long bulb because of the capacitor's resistance. The current flow will slow as a result and the long bulb will begin to light while the round bulb begins to dim. This will continue until the capacitor is charged, which will cause it to resist the current flow and will cause it to all flow through the long bulb. This will cause the long bulb to be bright and the round bulb will be dimly lit.

c) Sketch three schematic diagrams with a capacitor in parallel with the long bulb. Color code the wires and show the bulb rays and arrow tails for the following cases:

immediately after connection:

mid-way through process:

steady state:

17. What is the effect of adding another round bulb in parallel? Set up the 3-bulb circuit in figure on the left, with a gap for a 4th bulb to be added. Then add the 4th bulb to form the circuit in figure on the right. To switch back and forth between the two circuits, you can add the 4th bulb and its socket, and simply unscrew the 4th bulb to break the connection.

__Hypothesis:__ By adding another round bulb that is parallel to the middle round bulb of the circuit above, the flow rate increases in the circuit, causing all of the bulbs to be brighter.

__Data:__ media type="file" key="Movie on 2011-10-25 at 13.27.mov" width="300" height="300"

__Conclusion:__ Based on the data above, we can see that when the parallel circuit is added, the bulbs that are in series (1st and 4th) get brighter, but the parallel bulbs do not get any brighter. This is because the flow rate increases along the circuit, but is divided between the two parallel bulbs. As a result the amount of charge in the circuit flowing to each parallel bulb remains the same or similar to what it initially was, while the outer bulbs are brightened by the increased flow rate.

18. How does the addition of another branch affect flow rate and pressure in the wires? Assemble a circuit with a 3-cell battery and a round and long bulb in series. Using a compass, measure the flow rate in wires A and B. Add a branch with a second long bulb parallel to the long bulb, but don't make the connection. Predict what will happen to the bulb brightness and flow rate when the connection is made. Repeat for a round bulb and for a connecting wire.

__Hypothesis:__ By adding a parallel wire to the circuit, the flow rate of the circuit will increase and the pressure of the wires will change based on what is on the wire parallel to the long bulb.This will cause the flow rate to increase but the pressure in the wires will remain the same in each of the circuits except for the third one where the long bulb is short circuited.

__Data:__

__Conclusion:__ Based on our data, the addition of a parallel wire affects the circuit relative to the resistance on that wire. In circuit 1 there is a long bulb that is added, causing some resistance on the wire. The current flow of the circuit increases and can be seen by how the round bulb gets brighter, but the electric pressure in the wires stays the same. In the second circuit a round bulb is added which has less resistance than the long bulb in the first circuit. This causes flow rate to increase by even more, but the electric pressure does not change. In the third circuit there is simply a wire that is placed parallel to the long bulb. This causes the long bulb to be short circuited, and cut off from the entire circuit, going out. The flow rate increases dramatically, with the round bulb being the only source of external resistance. The pressure in the wires changes for the wire connecting the long bulb, which loses all change in electric pressure and all current flow.

19. What is the effect of decreasing the resistance of right side of the circuit on: a) the flow rate through the battery; b) the pressure difference across the battery; c) brightness of the left bulb

__Hypothesis:__ Decreasing the resistance of the right side of the circuit will in crease the flow rate through the battery, will not have an effect on the pressure difference across the battery, and the long bulb on the left in the circuit will not change it's brightness.

__Data:__ it causes the charge flow (measured by needle on compass) to increase in the circuit, but the bulbs remained the same brightness. The pressure difference in the circuit remains the same || When the round bulb is added in place of the long bulb it causes the flow rate to increase to more than it was in Circuit A (measured with a compass) but the long bulb remained the same. The pressure difference in the circuit remains the same. || When a second parallel round bulb is added to Circuit B and creates Circuit C, the flow rate increases in the circuit, but the long bulb remains the same. The pressure difference in the circuit remains the same. ||
 * Circuit A || Circuit B || Circuit C ||
 * When the long bulb is connected to the circuit

__Conclusion:__ Based on the data from the three circuits above, it can be determined that by decreasing the resistance of the right side of the circuit has a direct affect on the flow rate through the battery, but has no effect on the pressure difference across the battery, and no affect on the brightness of the left bulb. The flow rate was 'measured' by placing a compass under a wire in each circuit, and there was a pattern that as the resistance on the left side of the circuit decreased, the amount the needed moved increased, which indicates an increase in flow rate. We know that the pressure difference of a circuit is NOT affected by a parallel series, so it could not have any affect how much resistance there is in the left side of the circuit. We also notice in creating these circuits that the left long bulb stays the same brightness in each circuit. This indicates that there is no change in brightness of the left bulb in these circuits.

20.
Practice Set: What determines [|Pressure in the Wires]? 1. For the following questions, consider these circuit diagrams:

a) How do the flow rates at A, B, and C compare to each other? Explain.

The flow rates at A, B, and C are all the same. This is because the flow rate of a circuit is the same at all points in the series. In this case the points are before and after a bulb, and there will be no change in flow rate caused by the bulb while the circuit is running.

b) How do the electric pressures at points A and C compare to each other? Explain.

The electric pressures are high before the bulb at point A, and low after the bulb at bulb C. This is because the bulb has resistance, and needs an electric pressure to force the current across the filament. Since current flows from areas of high electric pressure to areas of low electric pressure, we know that point A before the bulb must have high pressure and point C after the bulb must have low pressure. This causes the current to flow across the bulb from high pressure to low pressure.

c) How do the flow rates at X, Y, and Z compare to each other? Explain.

The flow rate is higher at y than at z. This is because Y is connected to a parallel round bulb while Z is connected to a parallel long bulb. The round bulb will allow current to flow faster than the long bulb will, causing point Y to have a faster flow rate than at point Z. The flow rate at point X will be the fastest of the points because the current there has the ability to flow along wire Z or wire Y. Because of this division in the circuit, the current of wire X goes to both wires Y and Z, allowing it have an even faster flow rate.

d) How do the electric pressures at X, Y, and Z compare to each other? Explain.

The electric pressure at X, Y, and Z are all the same. This is because the electric pressure of a circuit is not affected by having parallel series. The only thing that separates the battery from X, Y, and Z is a wire with no resistance. As a result there is no change in electric pressure for X, Y, or Z.

2. The wires that an electric company connects to your house can be pictured as being attached to a very big battery having an electric pressure difference of 120 volts (instead of the 4.5 volts provided by your battery pack). The electric lights and appliances in your house are designed to operate properly only when there is a 120 volt pressure difference across them and they are all connected in parallel. What is the advantage of parallel wiring, rather than series?


 * By having the lights and appliances in parallel wiring, all of the items in the circuit get the same 120 volts of energy from the power source. If the circuit was series oriented, then some of that voltage would be used up by each item in the circuit, and the later items in the circuit would only get a fraction of the 120 volts. Also if it was in a series, the entire circuit would not work if even one appliance or item in the circuit were to disconnect or 'die'. In a parallel circuit all of the items get the 120 volts, and if an appliance becomes disconnected from the circuit, the other items will still work and the circuit will still be complete.

3. A typical house has many separate circuits, each of which has multiple parallel branches. In each circuit, the trunk leading to the parallel branches is wired in series with a fuse or a circuit breaker. A fuse melts or a circuit breaker opens if the current through it becomes greater than a certain value (typically 20 amperes). The purpose is to prevent the wires from overheating and possibly starting a fire when too many appliances are connected in parallel. It is also to prevent appliances from being damaged if voltage from electric lines to the house increases dramatically due to lightning or some other accident. How is a fuse or a circuit break able to “save” the wires and appliances from harm?


 * A fuse or a circuit break can "save" the wires and appliances from receiving too much current. Too much current, caused by a short circuit or increase in power (lightening) would cause the wires and appliances to receive a larger amount of energy than what it is made to handle. As a result the circuit would become very hot, and able to melt wires and damage the circuit of the appliances. This could even cause an electrical fire in your house. A fuse or circuit break will acknowledge the increase in energy in the current flow, and will close the circuit off, causing the current to stop and cool off if necessary. This will eliminate the threat of an increase in voltage and electric energy causing extreme heat in the circuit.

4. In the space below, draw a schematic diagram of a house circuit containing a TV, a computer, and a microwave oven; show the switches that control each appliance; and show a fuse or a circuit breaker designed to protect the circuit.




 * CB = Circuit Breaker TV = Television Comp = computer Oven = oven Battery represents power supply**

5. In a house, the branch wires may be attached to appliances and bulbs of different resistance. What is the relationship between the flow rate of charge in the main trunk wire of a house (coming in from outside) and the flow rate of charge in the branch wires?

The flow rate of charge in the main trunk wire of a house would be dependent to the flow rate of charge in the branch wires. Similar to how the flow rate of a circuit was dependent on the flow rates of the objects in parallel series' that we created, the flow rate of the main trunk wire will be dependent on the flow rates of all of the branch wires within the house. The current from the trunk wire will travel along the branch wires, and will flow within each wire at the fastest rate allowed by the resistance of that wire back to the main trunk wire. The flow rate of the main trunk wire will be the sum of the flow rates of these internal branches, as the current in the main trunk wire will flow into all of these branches.

6. A battery is connected to three long bulbs in series. After a steady state condition is reached, a fourth identical bulb is connected in parallel to bulb B. What effect does adding the bulb have on:



a) the pressure difference across bulb B? __no change__ b) the flow rate through bulb B? __decreases__ c) the pressure difference across bulb A? __no change__ d) the total or net resistance of the circuit? __no change__ 7. Refer to the circuit in question #6. Instead of adding a long bulb parallel to bulb B, consider adding a wire. What effect does adding a wire have on: a) the pressure difference across bulb B? __eliminated completely__ b) the flow rate through bulb B? __eliminated completely__ c) the pressure difference across bulb A? __increased__ d) the total or net resistance of the circuit? __no change__

21. Activity: Ammeter Voltmeter. Work with your classmates to investigate the circuits diagrammed in this [|Labsheet]. This will be submitted as a separate lab grade.

__Objective:__ To find how different bulb arrangements and combinations affect the amount of Voltage and Current readings in a circuit.

__Hypothesis:__ Color code each of the following circuits. Predict bulb brightness and flow rate, showing this with starbursts and arrowtails. Rank each of the circuits in terms of flow rate through the battery.

__Procedure__: Using an ammeter and voltmeter, measure the voltage and flow rate of different circuits. __Data:__ 3 || V a =6.87V V b =3.11V V c =3.35V V d =6.68V || a=0.33A b=0.33A c=0.33A || 8 || V a =4.48V Vb=2.29V Vc=2.20V Vd=4.46V || a=59.7mA b=58.8mA c=59.8mA || 7 || V a =7.73V Vb=3.3V Vc=4.5V Vd=7.65V || a=135mA b=133mA c=130mA || 6 || Va=7.2V Vb=6.5V Vc=0.8V Vd=7.09V || a=139mA b=139mA c=137mA || 2 || Va=4.13V Vb=3.86V Vc=3.83V || a=0.5A b=0.25A c=0.24A d=0.5A || 4 || Va=4.46V Vb=4.27V Vc=4.21V || a=171.8mA b=87.5mA c=87.8mA d=171.8mA || 5 || Va=4.44V Vb=1.3V Vc=1.1V Vd=0.8V Ve=0.6V Vf=4.24V || a=140mA b=135mA c=132mA d=130mA e=133mA || 1 || Va=6.74V Vb=6.48V Vc=6.61V Vd=6.4V Ve=6.54V || a=0.53A b=0.13A c=0.13A d=0.14A e=0.13A || __Analysis:__
 * Circuit || Measuring Pressure Difference || Measuring Flow Rate ||
 * [[image:Screen_shot_2011-11-06_at_2.03.48_AM.png width="204" height="160"]]
 * [[image:Screen_shot_2011-11-06_at_2.05.40_AM.png width="199" height="150"]]
 * [[image:Screen_shot_2011-11-06_at_2.06.18_AM.png width="202" height="157"]]
 * [[image:Screen_shot_2011-11-06_at_2.06.56_AM.png width="202" height="175"]]
 * [[image:Screen_shot_2011-11-06_at_2.07.29_AM.png width="209" height="161"]]
 * [[image:Screen_shot_2011-11-06_at_2.08.13_AM.png width="197" height="162"]]
 * [[image:Screen_shot_2011-11-06_at_2.08.46_AM.png width="202" height="168"]]
 * [[image:Screen_shot_2011-11-06_at_2.09.17_AM.png width="204" height="183"]]

__Discussion Questions:__

1. What units are used for measuring electric pressure? What term do the 'experts' use for electric pressure?
 * The units for electric pressure are Volts, and the experts, such as myself, use the term electric potential.

2. A good measuring device does not significantly interfere with the circuit being measured. In terms of being a good measuring device please describe A.) whether the resistance of the voltmeter is high or low B.) How should the voltmeter be connected in the circuit in relation to where you want to know the electric potential difference? C.) Why does the voltmeter need to have the resistance it does in order to be a good measuring device?
 * You prefer high so that it does not interfere with the circuit, and the current flows past it.
 * In parallel to where you are measuring the electric potential, connecting to each end of the area being measured.
 * Because the voltmeter must not become a part of the circuit, and create a parallel to the area being measured. With high resistance the current will not flow through the voltmeter and the circuit will not change.

3. What would happen if you connected a voltmeter in series with a circuit component? Why is this not appropriate for good measurements?
 * The voltmeter, with its high resistance, would stop the current flow in the circuit, changing the way it is. As a result, the data recorded would not be of the original circuit. These measurements are of a new and different circuit which are not what we are trying to measure.

4. You have three bulbs connected in series. The voltage drop across each bulb is 2.0 Volts. Are the bulbs identical? How do you know? What is the voltage across the battery?
 * Yes the bulbs are identical. I know this because the equation for voltage of a circuit in series has the same change it voltage across it. In this case they each have a change of 2 volts across the bulbs and are in series.

5. You have four bulbs connected in series. The voltage drop across the battery is 12 Volts. The voltage drop across bulb A is equal to 1 Volt, the drop across bulb B is 5 volts, the drop across bulb C is equal to 4 volts.

a) What is the voltage drop across bulb D?
 * 2 Volts

b) Which bulb has the greatest resistance?
 * Bulb B

c) Which bulb has the smallest resistance?
 * Bulb A

6. You have five bulbs connected in parallel. The voltage drop across the first branch is 10 Volts. What is the voltage drop across the battery? What is the voltage drop across the other branches?
 * 10 Volts across the battery and each bulb.

7. Complete the circuit below with the correct pressure difference values for each component by recording them in the spaces provided. Note that the voltmeter placed across the battery shows a value of 6.Volts.
 * Battery=6V=Va+Vb+Vc=Vd+Ve
 * Va,Vb, and Vc= 2V
 * Vd and Ve=3V

8. What units are used for measuring flow rates? What do the experts call flow rate?
 * The units are in Amps, and experts call it current.

9. A good measuring device does not significantly interfere with the circuit being measured. In terms of being a good measuring device, describe:

a) Whether the resistance of the ammeter is high or low?
 * the resistance should be low so that it does not affect the circuit while in series.

b) How the ammeter should be connected in the circuit in relation to where you want to know the flow rate?
 * The ammeter should be connected in series with the area that you want to measure.

c) Why the ammeter needs to have its resistance in order to be a good measuring device?
 * If the ammeter had a lot of resistance it would change the flow rate of the entire circuit, and would create a different circuit entirely. As a result the data would be useless. If the resistance is extremely low, however, it will not affect the circuit.

10. What would happen if you connect an ammeter in parallel with a circuit component? Why is this not appropriate for good measurements?
 * The ammeter would create a parallel in the circuit with low resistance, causing it to short circuit. All of the current would go through the ammeter rather than the area being paralleled, creating an entirely different circuit and incorrect measurements.

11. You have two bulbs connected in series. The current in the wire connected to the positive terminal of the battery is 1.0 Amps. What is the current through each bulb?
 * 1 Amp

12. You have three identical bulbs connected in parallel. The current in the wire connected to the positive terminal of the battery is 6 A. What is the current through each branch?
 * 2 Amps

13. A circuit containing three parallel branches. The first two branches have identical resistance, but the third branch’s resistance is half the resistance of the first two. If the current in the trunk wire is 12 A and the current in two parallel branches are each 3 amps, what is the current in the last branch of the circuit?
 * I=12=3+3+x
 * x=6A

14. In the circuit below the current through bulb 1 is 1 A, the current through bulb 5 is 6 A and the current through bulb 8 is 3 A.
 * 1) What is the current in the wire connected to the positive terminal of the battery?
 * 2) Color code the circuit and determine the voltage values across each bulb and the battery as closely as you can. You may assume that each cell in the battery has a pressure difference of 4V.

__Conclusion:__ Based on the experiments we performed, we have determined that there is a direct relationship between circuit setups and flow rate. When circuits are in series they have the same flow rate as the battery, and one another, but have less voltage and their voltages add up to the voltage of the battery. For parallel, however, the voltages are all the same and the flow rates of the branches add up to the flow rate of the battery.

22. T/F
 * 1) Charges move by themselves. __False__
 * 2) A capacitor and a battery operate on the same principle. __False__
 * 3) A potential difference is only on plates of a capacitor and not in region between. __False__
 * 4) Charge flows through a capacitor. __False__
 * 5) Designations of (+) and (-) are absolute. __False__
 * 6) Work is required to charge a capacitor. __True__
 * 7) There is no net charge on a capacitor. __True__
 * 8) A positively-charged capacitor plate only has positive charges on it. __False__
 * 9) Resistors consume charge. __False__
 * 10) Electrons move slowly (relative to the speed of light) through a circuit. __True__
 * 11) Charges slow down as they go through a resistor. __False__
 * 12) Current is the same thing as voltage. __False__
 * 13) There is no current between the terminals of a battery. __False__
 * 14) The bigger the size of the resistor, the larger the resistance. __False__
 * 15) A circuit must have a closed loop of conducting materials for current to flow. __True__
 * 16) Current gets "used up" as it flows through a circuit. __False__
 * 17) A conductor has no resistance. __False__
 * 18) Current is an excess charge. __False__
 * 19) Charges that flow in circuit are originally from the battery. __False__
 * 20) The bigger the battery, the more voltage is provided to the circuit. __False__
 * 21) Batteries create energy out of nothing. __False__
 * 22) Generating electricity requires no work. __False__
 * 23) Batteries have electricity inside them. __False__
 * 24) Electricity only travels //from// a power generating station along the cables to houses. __False__
 * 25) Electricity is used up by a lit bulb, which causes less current on one side of the lamp. __False__

23. Test on Wednesday October 26th

=Part 3: Quantitative Analysis of Electric Circuits=

1.
Notes on current. Do [|Chapter 20 Guiding Questions] #1-6, in class 10/27.
 * NOTES 10/27:**


 * Guiding Questions #1-6:**

1. What is the definition of current?
 * The rate of flow of electric charge through a circuit measured in the quantity of charge per unit time. It is not how fast the charges move in the current, but how many of them pass at one time.

2. Conventional flow is the direction of motion of positive charges.

3. What is wrong with this statement?
 * Conventional flow is the direction of charge from the positive to the negative. In truth, the opposite is true. The electron flow is from the negatively charged end to the positively charged end. It is the negative electrons that serve as the charges, making the real flow opposite to the conventional flow theory.

4. Why doesn’t it matter?
 * Because the amount of charge involved and the voltage involved are not changed. All that is changed by this is the direction of flow, which has no real affect on the circuit.

5. How fast do charges move when moving in a wire?
 * Slow. Although there is little resistance, the charge flows in random zigzag patterns which causes it to take longer to flow along the circuit.

6. If a current of 80.0 mA exists in a metal wire, how many electrons flow past a given cross section of the wire in 10.0 min?
 * (80 x 10 -3 A) x (60s/1min) x 10 min x 1e - /(1.6 x 10 -19 J) = 3 x 10 20 e -

2. Read and Summarize //Lesson 2 (Electric Current) on Electric Circuits at the Physics Classroom: [|Electric Circuits] .// Use [|Method 4]. **//Post on your wiki//**.

What is an electric circuit? What are the requirements of a circuit? What is electric current? What is power, and how does it 'put charges to work'? What are common misconceptions regarding electric circuits?
 * A closed loop through which charges can continuously move in a current with the help of a power source.
 * A loop must be formed of conductors which allow current to flow continuously, and a power source must provide energy and electric potential so that the charges move along the circuit.
 * Electric current is the amount of charges that flow past any point of a circuit at one period of time.
 * Power is the rate at which electrical energy is supplied to a circuit or consumed by a load. This power is supplied by a power source, such as a battery or electric company. [[image:u9l2d3.gif]] This power causes charges to move within the circuit "putting them to work" as they light bulbs, energize appliances, and many other great things. The unit of electrical power is the watt. A watt is equivalent to 1 Joule supplied per second, or 1 watt = 1 Joule / Second.
 * Batteries are not rechargeable. They experience a chemical reaction to produce energy and new chemicals, and when there is not enough of the original chemicals left, the reaction does not occur to create energy. The battery is 'recharged' by giving more energy to the battery, reversing the reaction to form the original chemicals.
 * Charge does not originate from the battery, it is always in the wires and objects of a circuit, and the charges are forced to move by the energy of a battery, which causes a charge flow.
 * Charge is not used up as it flows through a circuit. It is resisted by resistors and bulbs, but not used up. The current creates friction in a bulb which cause it to light, but the current is not used up in the process.

3. Notes on Resistance. Do [|Chapter 20 Guiding Questions] #7-14, in class 10/27.

7. What is the relationship between potential difference and current? What is this relationship called?
 * Potential difference and Current are directly related based on the resistance of the circuit. This relationship is called Ohm's law, and the equation to represent it is: V = I*R

8. Distinguish between a graph of current vs. potential difference for an ohmic and non-ohmic material. Explain why they look this way.
 * The graph of current vs. potential difference of an ohmic material is going to be a straight line. This line can be determined by using the equation V = R*I similarly to the equation of graphing y = m*x where m is the slope. The slope of this graph for an ohmic material, as a result, will be equal to the resistance of the circuit or object. When the object is non-ohmic, the graph does not follow this equation, and the resistance varies. In the cases we have seen the graph formed half of a positive parabola in which the slope (resistance) increases as the current and potential difference increase.

9. Upon what factors does resistance depend?
 * Resistance depends on potential difference and current. If there is no potential difference the circuit will not flow across the resistor. If there is no current, then there is no flow to resist.

10. What are 3 ways to calculate resistance? When would you use one vs. the other?
 * Resistance can be calculated using R = V/I, R = , and R =

11. How is mechanical power related to electrical power?
 * Mechanical power can be used to generate electrical power, or can be the product of electrical power. This was seen when the Genecon was used to light the bulbs, and when a battery caused the Genecon to spin by itself.

12. What will be the resistance of each of the following resistors according to the resistor code?
 * 1) red, brown, red, gold = 2100 ± 5%
 * 2) grey, blue, orange = 86000 ± 20%
 * 3) white, violet, black, silver = 97± 10%
 * 4) blue, violet, green, gold = 6700000 ± 5%

13. A given wire has a length L, a diameter d and a resistance R. [Assume that the wires are cylindrical!] What will happen to the resistance of this wire if it is stretched to twice its original length? If its diameter is doubled? If the length of the wire is doubled while the diameter is also doubled? Explain your reasoning!

14. A piece of unknown gauge 34 wire 50.0 cm long is attached across a 6.0 Volt battery resulting in a current flow of 0.495 Amperes. What is the resistivity of this wire?

4. Read and Summarize //Lesson 3 (Electrical Resistance)// on Electric Circuits at the Physics Classroom: [|Electric Circuits]. Use [|Method 4]. **//Post on your wiki//**.

What is the journey of a typical electron? What is resistance?
 * A typical electron travels slowly (compared to the speed of light) along a circuit, and this is because the path that the electron takes is zigzag and in no way direct around the circuit. The current as whole moves along the circuit directly, but the electrons moving go back and forth along the conductors in a random pattern, and progressively move in the forward direction that the battery is pushing the charges to move in. The current will flow form areas of high electric potential to areas of low potential.
 * is the hindrance to the flow of charge. For an electron, [[image:http://www.physicsclassroom.com/Class/circuits/u9l3b2.gif width="169" height="97" align="right"]]the journey from terminal to terminal is not a direct route. Rather, it is a zigzag path that results from countless collisions with fixed atoms within the conducting material. The electrons encounter resistance - a hindrance to their movement. While the electric potential difference established between the two terminals //encourages// the movement of charge, it is resistance that //discourages// it. Resistance is what prevents charge from properly flowing.

What is Ohm's Law?
 * Ohm's Law states that the electric potential between two points is equal to the current times the resistance in between these two points on the same current. The equation can be written as ∆V=I*R and is crucial for calculating the voltage, current, and resistance in an object or objects within the same circuit.

Shall we revisit Power?
 * Power in electricity can be regarded as the amount of watts per an amount of time. In most cases, it is Kilowatt Hours. The equation for calculating the power delivered to the circuit or consumed by a load was derived to be P=∆V*I. This equation can be manipulated using the knowledge that ∆V=I*R to create the equations P=I 2 R or P=V 2 /R.

5.
Do Ch. 20 problems in Text # 5,7,11,18 (Resistance/Resistivity) in HW Journal, due 10/28.

= 6.Ohm's Law Lab Report = Do Experiment: [|Ohm's Law] (10/27- 10/28) - Post lab report... here is the [|Rubric], due Monday 10/31.

__Purpose:__ To use data that will determine the relationship between Pressure Difference and Flow Rate, as well as to better define the difference between Ohmic and non-ohmic materials.

__Hypothesis:__ Pressure difference and flow rate will have a direct relationship. As pressure difference increases, flow rate will increase, and as flow rate increases, the pressure difference will increase. We can suspect this because of a relationship noticed when batteries are added to a circuit with bulbs. When more batteries are added the bulbs get brighter, indicating a greater flow rate.

__Procedure:__

Before you do anything, make sure the multimeter is set to record as an ammeter by setting the knob to "200mA". Then, set the variable power supply to a certain voltage that is not too much for a resistor and not too small so that there is a good reading for a multimeter (round bulb = .1-3 V, long bulb = .1-6 V, resistors depend on the size of the resistor). Use wires to connect the variable power supply to one end of ONE resistor, and to one end of the multimeter. Have the end of the multimeter that is not already touching the wire to the power supply touch the end of the resistor that is not already touching the wire to the power supply, completing the circuit. This will give you a reading on the multimeter which is the number of Milli-amps of charge in the circuit for that voltage. Then, repeat this process with different voltages that give readings from the resistor until you have enough data to make an accurate graph (we did five voltages). Once you have enough, switch the resistor being tested and repeat the process until you have enough data for each of the resistors to make a proper conclusion about Ohm's Law.

__Materials:__
 * variable power supply
 * batteries/holders
 * long/round bulb and socket
 * assorted resistors
 * mulitmeter
 * lead wires

__Data:__



__Sample Calculations:__

R = V/I

R = 5V/.0050A

R = 1000Ω

% Error = [(|Calculated - Predicted|)/Predicted] * 100

% Error =[(|983.6-1000|)/1000] * 100

% Error = 1.64%

% Difference = |((value1-value2)/(value1+value2))/2| * 100

% Difference = |((.0050-.0061)/(.0050+.0061))/2| * 100

% Difference = 4.95%

__Graphs:__





__Analysis:__ The above graphs show how voltage, flow rate, and resistance are related to one another in bulbs and resistors. In the graph of our resistors, we can see that these graphs are almost perfectly linear, with an R 2 value of .99. The equation for these graphs follows the equation of Ohm's Law, V = IR, with V as the y-value and I as the x-value. As a result we can see that the slope of these equations is the R resistance for each resistor. This shows how the current and voltage through a resistor affect one another, but the resistance is not changed in Ohmic materials such as these. In the other graph, however, we notice that the slope of the lines change as voltage and current change. As a result, there is no constant slope along the graph, indicating that these bulbs do not follow Ohm's law and are not ohmic. The changing slope indicates that the amount of voltage and current through a bulb will change the amount of resistance the bulb has on the circuit. These bulbs are non-Ohmic materials.

__Discussion Questions:__

1. In terms of experimental data, how is resistance defined and what are its units?


 * Resistance is the slope of the lines of progression, which can be defined as Voltage divided by Flow Rate.

2. Imagine that you had a third resistor that has a much smaller resistance than the ones used in the lab activity. A.)Sketch a graph of pressure difference vs. flow rate that shows your 2 original resistors and this new resistor (sketch them on the same axes). Clearly label the lines.



B.)Explain why you drew it this way.


 * Because according to Ohm's law, V = IR. With V as the y-coordinates and I as the x-coordinates, the Resistance must be equal to the slope of this graph. Therefore a resistor with much less resistance will have a much smaller slope, as seen above.

C.)How would the flow rate through this resistor change as the pressure difference decreases?


 * In order to keep the same resistance, the flow rate would have to decrease in a direct ratio to how much the pressure difference decreases. This is because the flow rate and pressure difference have a direct relationship when they change the same amount as one another.

3. Assume that resistor A has 10 times the resistance of resistor B. What would a graph of resistance vs. current look like for these two resistors (sketch them on the same axes)? What about a graph of resistance vs. voltage? Justify your answers.

__Resistance V. Current:__



In the graph of Resistance V. Current I knew that the amount of current in a circuit has an affect on the amount of voltage, but it did not affect the amount of resistance involved. As a result, the resistance value does not change when the current flow increases or decreases.

__Resistance V. Voltage:__



In the graph of Resistance V. Voltage I knew that the amount of Voltage in a circuit has an affect on the amount of current flow, but it did not affect the amount of resistance involved. As a result, the resistance value does not change when the voltage increases or decreases.

Examine the graph of electric pressure difference vs. flow rate below.



4. Is this resistor Ohmic or non-Ohmic?


 * This resistor is Ohmic. I know this because the graph of Voltage (∆V) v. Current (A) is linear, indicating a direct relationship between current and voltage. This linear pattern indicates that there is a single slope which represents a single resistance, and follows the equation R = V/I.

5. What is the resistance of the object from which this data was collected? (Show your work.)

R = ∆V/I

R = (5)V/(1)I

R = 5 Ohms

__Conclusion:__ Based on our graphs, the hypothesis was correct: There is a direct relationship between the electric potential and the flow rate in a circuit. This can be seen in the brightness of a bulb when additional batteries are added, as well as in our results when testing the resistance of different resistors with an ammeter. For the resistors and bulbs tested, it can be seen in the graph that as the electric potential increases the flow rate increases, and this was true for all cases. We were able to calculate the amount of resistance using Ohm's law (R = V/I) and we determined that the slope of our graphs of Voltage v. current is the resistance at that point. Our % error was very small, and this is because our resistors were very precise. The gold bar at the end of each resistor indicated a ±5% error in resistance to what is projected, and for some points we even got an error of 0%. The power source was also responsible for accurate results, as it supplied exactly the amount of voltage we wanted to the resistor. Because the power source and the resistors were precise, the percent of error was going to be minimal. In the six volt measurement for the smaller resistor we found that the measurement was .0061 in the ammeter. When you divide the voltage by this value you get the resistance which equals 983.6 Ohms. To find error we use the equation (% Error = [(|Calculated - Predicted|)/Predicted] * 100) and get a result of 1.64% error. The error could have come from the resistor. This 1.64% is less than the 5% guarantee by the manufacturer, meaning that the resistor could be slightly less or more resistant than what is indicated. The other source of error is the ammeter. The ammeter was getting multiple measurements that varied amongst a few possible points. As a result, we picked a value that was the most common and the most centered amongst what was displayed. This number may not have been completely accurate, and could be a source of error.

If possible, I would get resistors that have less margin for error. The resistors we used had an error guarantee of ±5%, and caused our results to be slightly inaccurate. If the resistor was ±1% or even less, our data would be more precise and there would be less error. A second way to reduce error would be to measure with more precise ammeters. The ones used in class often got varied results, and as a result the data was not reliable. This variation in measurements led to some error in the results and the graphs.

// 7. // // OPTIONAL // Do Gizmo [|Ohm's Law]. Go to "Lesson Materials" for the worksheet, due 10/31.

8. Notes on Series and Parallel Circuits. Do [|Chapter 20 Guiding Questions] #24-28, in class 11/1.

9. Read and Summarize //Lesson 4 (Circuit Connections)// on Electric Circuits at the Physics Classroom: [|Electric Circuits]. Use [|Method 4]. **//Post on your wiki//**

What are circuit symbols and circuit diagrams?


 * Circuit symbols are symbols to represent the compnents of a circuit. These symbols are used in certain drawings of circuits, rather than drawing and labeling the components as they actually appear. Some of them look like this: [[image:u9l4a2.gif]]. Circuit diagrams are drawings of a circuit. They can be drawn as they appear in real life, or as a schematic drawing, which is a drawing using the symbols shown above. These schematic diagrams are easier to interpret and read for someone who is trying to understand the circuit and how the current flows.

What are the two types of connections?


 * The two types of connections in a circuit are in series and parallel. An in series connection is a connection between parts of a circuit that are along the same direct path from one end of a power source to the other. When objects are connected in series they are on the same path for current along the circuit, and one receives the current before it goes to the next object in series. A parallel circuit is one in which objects are connected, but they are not necessarily on the same path in the circuit as one another. This type of connection involves a junction which allows current to flow to multiple different branches which are parallel to one another and both complete the circuit.

What are series circuits?


 * An in series connection is a connection between parts of a circuit that are along the same direct path from one end of a power source to the other. When objects are connected in series they are on the same path for current along the circuit, and one receives the current before it goes to the next object in series. This causes the objects in series to directly affect one another based on how resistant they are.

What are parallel circuits?


 * A parallel circuit is one in which objects are connected, but they are not necessarily on the same path in the circuit as one another. This type of connection involves a junction which allows current to flow to multiple different branches which are parallel to one another and both complete the circuit. A parallel circuit increases the flow rate of the circuit by creating multiple paths for current to travel. Like adding an additional lane to a highway, a parallel connection adds more room for the current to move, reducing the overall resistance of the circuit.

What are combination circuits?


 * Combination circuits are circuits which have both types of connections: in series and parallel. This can be done by having the circuit in series, with one segment that has a parallel branch or in many other ways. By looking carefully at a combination circuit, it can be seen how the properties of parallel and in series connections affect the entire circuit.

10.
Do Ch. 20 problems in Text # 43,44,47,52,54,119 (Series and Parallel Circuits) in HW Journal, due 11/2

// 11. // // OPTIONAL // Do Gizmo [|Circuit Builde] r. Go to "Lesson Materials" for the worksheet.

12. Notes on Combination Circuits. Do [|Chapter 20 Guiding Questions] #29, in class 11/1.

13. Do Ch. 20 problems in Text # 58,60,61,63,65,124 (Combination Circuits) in HW Journal, due 11/3.

// 14. // // OPTIONAL // Do Gizmo [|Advanced CIrcuits]. Go to "Lesson Materials" for the worksheet.

15.
Notes on Kirchoff's Rules. Do [|Chapter 20 Guiding Questions] #30-38, in class 11/1.

16. Do Ch. 20 problems in Text # 74,76,77,78,79 (Kirchoff's Rules) in HW Journal, due 11/4.

= 17. Kirchoff's Rules Lab Report = Do Experiment: [|Kirchoff's Rules] - Post lab report... here is the [|Rubric], in class 11/3, due 11/4.

__Purpose:__ To determine how currents split in multi-loop circuits.

__Hypothesis:__ As the currents split in a circuit, the current will divide between the parallel paths created, allowing more current to flow at once. This increases the flow rate of the Current because the current will have more charges flowing at one time, regardless of the resistance in each path.

__Procedure:__ In our class four circuits were pre-made by Ms. Burns and labeled A,B,C, and D. The amount of resistance in each resistor were written next to them, and he had to find the rest. Starting with one of the circuits, made a schematic diagram of the circuit as this will make it easier to understand what is happening with the current. If possible, compare your schematic diagram with other people's to make sure that it is correct. Then, use a multimeter to measure the current and voltage at each resistor. To measure the current, set the multimeter to "200 mA", remove the wire from the resistor chosen, connect the wire to one end of the multimeter and connect the resistor to the other end of the multimeter to complete the circuit. When this is done and you have gotten a reading, re-connect the wire to the resistor and remove the multimeter from the circuit. Set the multimeter to "20 V", and place the positive wire of the multimeter on one end of the resistor and the negative wire of the multimeter to the other end of the resistor. This will give you the voltage passing through the resistor. Repeat this process for all of the resistors and organize the data neatly. (NOTE: BATTERIES ARE RESISTORS. FIND THE VOLTAGE AND CURRENT OF THEM ALSO AND USE THIS TO CALCULATE THE BATTERY'S RESISTANCE!). Use this data and your knowledge of Ohm's Law in order to draw a conclusion about how current splits in multi-loop circuits and to better understand Kirchoff's Rules.

__Materials:__
 * Resistors
 * Wire Leads
 * D-cell Batteries
 * Several Digital Multimeters (DMM)
 * (2) power supplies
 * 3 – 4 resistors
 * connecting wires

__Data:__


 * Circuit A:**
 * || Resistance(Ω) || Voltage(V) || Current (mA) ||
 * R1 || 100Ω || 2.05 V || 20.6 mA ||
 * R2 || 560Ω || 4.46 V || 8.00 mA ||
 * R3 || 300Ω || 2.39 V || 7.80 mA ||
 * R4 || 300Ω || 3.96 V || 12.9 mA ||
 * R5 || 100Ω || 1.54 V || 15.7 mA ||
 * B1 ||  || 6.08 V || 22.0 mA ||


 * Circuit B:**
 * || Resistance(Ω) || Voltage(V) || Current(mA) ||
 * R1 || 500Ω || 3.84 V || 7.7 mA ||
 * R2 || 1000Ω || 6.14 V || 6.2 mA ||
 * R3 || 750Ω || 1.17 V || 1.5 mA ||
 * B1 ||  || 10.03 V || 7.7 mA ||
 * B2 ||  || 5.00V || 1.5 mA ||


 * Circuit C:**
 * || Resistance(Ω) || Voltage(V) || Current(mA) ||
 * R1 || 1000Ω || 9.2V || 9.5mA ||
 * R2 || 820Ω || 0.48V || 0.6mA ||
 * R3 || 680Ω || 5.5V || 7.9mA ||
 * R4 || 560Ω || 0.54V || 0.9mA ||
 * B1 ||  || 9.99V || 9.6mA ||
 * B2 ||  || 5.03V || 8.0mA ||


 * Circuit D:**
 * || Resistance(Ω) || Voltage(V) || Current(mA) ||
 * R1 || 100Ω || 4.87V || 45mA ||
 * R2 || 200Ω || 1.97V || 9.4mA ||
 * R3 || 47Ω || 1.67V || 34.9mA ||
 * B1 ||  || 4.50V || 31.4mA ||
 * B2 ||  || 1.56V || 8.1mA ||
 * B3 ||  || 1.52V || 31.4mA ||

__Sample Calculations:__


 * Circuit A:**


 * Circuit B:**


 * Circuit C:**


 * Circuit D:**

__Analysis:__


 * For Circuit D:**

__Discussion Questions:__

1. Are the experimental values of the currents for the entire laboratory generally larger or smaller than the theoretical values expected for the currents?
 * My experimental values were very similar to my theoretical values, although there was a pattern of the experimental values being slightly higher than what was expected in the theoretical results.

2. It was pointed out in the laboratory that some error might be caused by neglect of the internal resistance of the //emf//. Would the internal resistance cause an error in the direction shown in your answer to question 1? State your reasoning for the direction of any error caused by the internal resistance.
 * No, this internal resistance would not get rid of this error, and would even make the theoretical values lower and farther from the experimental results.

3. An ideal ammeter has zero resistance. Real ammeters have small but finite resistance. Would ammeter resistance cause an error in the proper direction to account for the direction of your error indicated in question 1? State your reasoning.
 * No, due to Ohm's law this would lower the experimental current, not helping with the error.

4. The connecting wires in the experiment are assumed to have no resistance, but in fact have a finite resistance. Would this error be in the proper direction to account for the direction of the error stated in your answer to question 1? State your reasoning.
 * No, this would not help with the error stated in question 1. As mentioned before, the experimental value was higher than the theoretical value. By including the finite resistance in the wires, according to Ohm's Law, would lower the theoretical value for current, making the problem slightly worse.

5. What is the meaning of any current values obtained in your solutions that are negative?


 * A negative value for currents indicate that the ammeter's wires are connected in the opposite direction of the current flow direction. This simply means that the positive and negative wires should be switched, and the negative value displayed is the opposite of the actual current flow.

__Conclusion:__

My hypothesis was correct, and the current divided between the parallel paths. Also, we know that this caused an increase in current flow. We also discovered in this experiment that as the current divides, it divides into currents that are equal to the initial current. We can see this, for example, in Circuit D when I1 split into I2 and I3. The corresponding equation was this, I1= 45mA and I2+I3=34.9+9.4=44.3 mA, which shows that I1=I2+I3. This could be seen in all of the circuits where it split into parallel series'. As shown in the analysis, all my theoretical results were very similar to my experimental values, and all the circuits showed that each result differed by the similar amounts. The error of this lab could come from a few different places. First, we assumed that the multimeter, wire, and battery/power source, had no resistance even though they have a little resistance. Depending on the use of them, they could have had caused error in the results. Lastly, the resistors have areas of numbers, not an exact value, and we just took the ohms of the resistors. The resistors had accuracy ranges of ±5,10, or even 20% which leads to error in the amount of theoretical resistance. In order to make the lab more accurate, it would be best to use more accurate resistors (less than ±5%). This would allow us to be more certain of what the resistance of the resistors are in comparison to their theoretical, face value. This led to error in our data, as we had no way of knowing whether our calculations could be wrong, or if the resistor was what the theoretical value was. Another way to make the lab more accurate would be to measure for the battery's internal resistance to take that into account. By doing this we would have included more resistance which affects the current of the circuit. This lab is valuable way to learn how to properly use Kirchoff's Rules, which are very significant in electronics and Physics. Finally, it gives us the ability to find values of even the most complicated circuits, and can be used in a household to determine how much current appliances will receive. Household circuits are extremely complex with many parallel branches to supply energy to numerous appliances, devices, and lights. As a result, it is important to be able to calculate how much current will go to each appliance and bulb, that way they can be certain that there is enough energy, but not too much to cause damage.

18. Quiz on Friday 11/4... on Electric Circuits

19. Notes on power. Do [|Chapter 20 Guiding Questions] #15-17, in class 11/4.

20.
Do Ch. 20 problems in Text # 25 (Power) in HW Journal, due 11/4.

// 21. // // OPTIONAL // Do Gizmo [|Household Power]. Go to "Lesson Materials" for the worksheet, due 11/7.

22. Notes on //emf//. Do [|Chapter 20 Guiding Questions] #18-23, in class 11/4.

23. Do Ch. 20 problems in Text # 67, 68,71 (//emf)// in HW Journal, due 11/4.

24. Review all 11/7 & 11/8

25.
Practice AP Problems: do all 5 from this packet, in class on 11/7 and 11/8, due on Monday 11/14.

26. Test on 11/9.

27. The test on Electric Circuits (Chapter 20) is scheduled for 11/9.