Photoelectric+Effect

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= Part 1 = toc Discussion Questions about Video: >> KE is the kinetic energy of the ball after escaping the depression, and acts the same as KE in Einstein’s photoelectric effect. >> E is the energy of the hand pushing the ball, and is the same as the energy given to an electron from the photons of light that cause it to escape the metal surface. >> ∆GPE is the change in gravitational potential energy for the ball, and acts the same as the work function of a metal in Einstein’s photoelectric effect. 10.French Physicist Louis de Broglie questioned, “If light exhibits dual wave-particle behavior, why can’t any particle of matter, such as an electron, exhibit a wave nature?” 11.The Heisenberg Uncertainty Principle reflects the wave-particle duality of light and matter: The more we know about matter as a particle (well-defined position), the less we know about its momentum (wavelength) and vice versa. 12.What did each of these scientists contribute to Quantum Physics? 13.How does a solar-powered calculator work? 14.How does your cell phone’s digital camera work? 15.How does a laser work? 16.How do solar panels work? OK... Got it.Nice job ~EB
 * 1) Upon what physical quantity does the color of any glowing body depend?
 * The Energy in the glowing body determines the color.
 * 1) As the cells in a flashlight get weaker, the filament appears redder. Why?
 * This is because the filament has less energy, causing it to be of lower frequency, as can be seen in the equation E=hf where h is constant.
 * 1) The surface temperatures of Vega, our Sun, and Barnard’s star are 10,000 K, 6,000 K, and 3,000 K respectively. Which of these appears blue in color; red in color; yellow in color? Why?
 * Vega will appear as blue because it has the greatest energy, which means the greatest frequency as can be seen in the equation E=hf.
 * Our sun will appear as yellow because it has a middle amount of energy at 6,000K, and according to the equation E=hf it will have a frequency that matches yellow.
 * Barnard’s star will appear as red because it has very little energy shining from it, which means a small frequency which is the same as in red light
 * 1) What is the photoelectric effect?
 * The effect of photons giving energy to electrons in a metal which allows the electron to escape from the metallic surface.
 * 1) As a mechanical analog of the photoelectric effect, consider a ball at rest in a depression. If a sufficient amount of energy, E, is given to the ball of mass, m, by the push of the hand, it will roll up the hill and escape with velocity v. Write an equation of energy conservation for this situation and explain each term in the equation by analogy to Einstein’s photoelectric effect equation.
 * KE = E-∆GPE
 * 1) An ultraviolet light discharges a negatively charged electroscope.
 * 2) The effect is known as _Photoelectric Effect___.
 * 3) Why isn’t the effect noticed when a glass plate is inserted between the zinc plate and the UV light?
 * Because the glass blocks the high frequency ultraviolet light, the light’s photons are not able to reach the metal with enough energy to cause the photoelectric effect, and the electrons are unable to escape the metal.
 * 1) What does the work function usually denoted by **// Ψ //** represent?
 * The amount of work necessary to release the electrons from the metallic object.
 * 1) Rewatch the video at about the 7 minute mark. The upper half of the screen shows an electron trying to escape from the surface of the metal. The bottom half is a graph. The vertical axis represents the electric potential energy of the electron. As you watch the video, notice that the electron slides along the bottom line and slips up the edge to the bottom of the work function line. This represents the most energetic electrons, the ones that will escape from the surface if photons strike the surface with energy equal to or greater than the work function. If an electron absorbs a photon of ultraviolet light with energy **//hf//** greater than **// Ψ //**, what will happen to the electron?
 * The electron will escape from the metal and travel away with a kinetic energy equal to the difference between the photon’s energy (hf) and the work function ( **// Ψ //** ) which can be seen in the equation KE = hf - **// Ψ. //**
 * 1) Use the table of work functions of various metals on page 1.
 * 2) If green light will cause the photoelectric effect to occur in sodium metal, for which other metals listed will it definitely also eject photoelectrons?
 * Cesium
 * 1) What would be the effect of doubling the intensity of the light used?
 * Doubling the intensity of the light used would double the amount of electrons released from the metal.
 * 1) What would be the effect of changing the color of the light used, for example, from green to blue or ultraviolet?
 * If the frequency of the light changes, the energy of the released electrons will change proportionally. As the frequency increases, the energy increases in the electrons, and vice versa.
 * 1) How did de Broglie relate a particle’s momentum to its wavelength?
 * By combining the concepts that light behaves like waves, as well as like particles, he was able to use the equations E=mc^2 and f = c / (lambda), as well as E=hf, we can form the equation p=h/(lambda). NOTE: it was also necessary, since the light is a particle, to treat c as velocity which fits into the equation p=mv.
 * 1) In the de Broglie model of the atom, if electrons are viewed as waves circling the nucleus, why do they have to exist in orbits that increase a whole wavelength at a time?
 * Because the light behaves as a wave, and only when the orbits increase by integer values of the wavelength do the waves have constructive interference, and reinforce them in every orbit.
 * 1) Waves produce an interference pattern. How can the pattern be explained in terms of particle of light ?
 * As particles of light there is no way of predicting where each individual particle will appear. Based on probability in location, however, the light particles will appear more often in certain regions than in others, which will create a cluster where light appears and “interference” where there are less particles.
 * 1) To what do the white light spots correspond where the wave pattern hits the screen?
 * The white light spots the result from the double slit experiment correspond to a probability of where the light particles will end up
 * 1) How can a particle’s location be made more definite?
 * By increasing the amount of waves used of various wavelengths, we can better find the location of the particle.
 * 1) As the position of the wave becomes more definite, what happens to the momentum?
 * The momentum of the particle becomes less certain as the particle’s position becomes more certain.
 * 1) Planck
 * He discovered a relationship between the energy of particles leaving as a result of the photoelectric effect and the frequency of light that caused this. It can best be described in the equation E=hf where E is the energy, f is the frequency, and h is a constant that Planck solved for, which would be later named Planck’s Constant. This value is the direct relationship between the frequency of light and the energy produced.
 * 1) Einstein
 * Einstein’s work in Quantum Physics is best summarized by the equation E=mc^2, in which E is the energy, m is the mass, and c is the speed of light. This equation was crucial in using Planck’s work to relate the theories that light behaves like a wave and like a particle. This equation would be used with Planck’s constant by De Broglie to prove that light behaves as both a wave and a particle.
 * 1) De Broglie
 * De Broglie came up with the theory that light behaves as both waves and particles at the same time. He was able to combine Planck’s work and Einstein’s work to do so.
 * 1) Schrodinger
 * Schrodinger made the discover that with multiple waves of varying wavelengths, it is possible to cause a wave like pattern to be seen in a specific region. With this wave representing the position of the particle and the varying wavelengths graph representing the momentum, it can be seen that neither is known specifically, but have general region of possibility. This is the clearest understanding of the behavior of photons and electrons and most particles of the world.
 * 1) Heisenberg
 * The uncertainty principle, an understanding that one may never know both the exact position and momentum of a light particle. It is understood that the particle’s position and momentum have an indirect relationship, the more we know about it’s momentum, the less we know about the position and vice versa.
 * The light that strikes the solar plates cause electrons to jump at the other end of the opening, which has a receptor which can bring the photoelectrons into the circuit which powers the calculator. This energy can be used as electricity for the calculator.
 * When the picture is taken, the photons hit different parts of the lens at different frequencies and intensities, which can be formed into an image with the corresponding colors based upon the frequencies and intensities.
 * Lasers release photons to only hit a certain number of electrons, usually through a beam of light from a source that aims along a narrow path.
 * The light that strikes the solar plates cause electrons to jump at the other end of the opening, which has a receptor which can bring the photoelectrons into the circuit which provides power for the generator. This energy can be stored as electricity.

= Part 2 =


 * Part 2 QUESTIONS: **

> A. Increasing the intensity of the light beam > B. Decreasing the intensity of the light beam > C. Increasing the wavelength of light > D. Decreasing the wavelength of light > E. Increasing the frequency of light > F. Decreasing the frequency of light > G. Increasing the voltage of the battery > H. Decreasing the voltage of the battery > I. Replacing the target with a material that has a larger work function > J. Replacing the target with a material that has a smaller work function
 * 1) Suppose you set up the experiment so that the plate is ejecting electrons. Predict which of the following changes to the experiment could increase the maximum initial kinetic energy of the ejected electrons. (Select all that apply) Then test your prediction.

> A. Increasing the intensity of the light beam > B. Decreasing the intensity of the light beam > C. Increasing the wavelength of light > D. Decreasing the wavelength of light > E. Increasing the frequency of light > F. Decreasing the frequency of light > G. Increasing the voltage of the battery > H. Decreasing the voltage of the battery > I. Replacing the target with a material that has a larger work function > J. Replacing the target with a material that has a smaller work function
 * 1) Suppose now you set up the experiment so that the light intensity is non-zero but the plate is NOT ejecting electrons. Predict which of the following changes to the experiment could make the plate start ejecting electrons? (Select all that apply) Then test your prediction.

> A. The force exerted on the electrons by the battery > B. The beam of light shining on the plate > C. Both A and B. > D. Neither A nor B.
 * 1) What causes the electrons to be ejected from the left plate in this simulation?


 * 1) Light is shining on a metal and electrons are being emitted. You turn the intensity down very very low. What do you observe? What conclusions can you draw about light, and why? how it is or is not consistent with what you would expect to observe if light matched the classical wave model and with what you would expect to observe if it matched the photon model of light.


 * As the intensity of light decreases, I can clearly see that the number of electrons that are emitted decreases drastically. Based on this observation, it is clear that the intensity of the light directly impacts the amount of electrons that are able to escape the metallic surface. The KE remains the same, indicating that intensity does not impact the KE of the electrons. Classical wave model would claim that as intensity increases, the amount of energy increases and therefor more KE.


 * 1) Light is shining on a metal plate and electrons are being emitted. Without changing the intensity, you make the wavelength longer and longer. What do you observe? What conclusions can you draw about light, and why? how it is or is not consistent with what you would expect to observe if light matched the classical wave model and with what you would expect to observe if it matched the photon model of light.


 * As the wavelength of the light increases, the velocity with which the electrons travel increases, and there are less electrons traveling out of the metallic surface. Based on these observations, we can conclude that the wavelength of light direct impacts the amount of energy that the electrons receive from the lights. The greater the wavelength the less energy given to the electrons, and because of this the electrons escape with less kinetic energy remaining and there are fewer electrons that can escape. Classical wave model would claim that no matter the wavelength, over time, the electrons would gain enough energy to be ejected.


 * 1) In the photoelectric effect experiment, the graph of current vs battery voltage for a metal with light of a particular frequency shining on it looks like the curve below. This graph represents **current vs voltage** for **200nm light** shining onto **Cadmium (Cd)** which has **a work function of 4.07 eV**.

a) Explain your reasoning for __why__ this curve has the shape that it does. In your answer, you should address: Why is current level at V>0, why does current go to zero at some negative voltage and what determines that voltage, and why does current start decreasing steadily at V<0?
 * To explain this graph we must start with when voltage in the battery=0, we notice that the current has a value that is generated entirely by the photoelectric effect. From this point in the positive direction, the current does not change, and this is because the voltage of the battery does not affect the amount of electrons, which escape from the metal, only, that it causes these electrons to move faster once they are free. When the Voltage is in the negative direction the battery has the opposite affect, decreasing the kinetic energy of the escaped electrons. The more negative the voltage is, the more significant this decrease in energy is, and because of this some electrons do not have the kinetic energy to make it across the gap, and return to the metal plate that they escaped from. Because of this, fewer electrons complete the circuit and the current decreases as seen in the graph. The voltage where the current is zero is the point when the voltage of the battery prevents any photoelectrons from completing the circuit.

b) What is the stopping potential in this situation (in eV)? (Remember stopping voltage is expressed as a positive number).
 * In this graph the stopping potential is the value of the voltage in which the graph first equals zero. At this point the voltage is exactly opposite the voltage that is generated by the photoelectric effect, and no current is created. The stopping potential, as a result, is the absolute value of the voltage in which the graph first reaches a current of 0 Amps. eV=KE=hf-(work function) eV=(6.26*10 -34 *3*10 8 )/(1.6*10 -19 *200*10 -9 )-4.07=2.17eV

c) In the graphs below, the gray curve is always the same and represents the situation you explained in part a (the current vs voltage for 200nm light shining onto Cadmium (Cd) which has a work function of 4.07 eV). The red curves now represent the current vs voltage after a change in the experiment. Use the graphs to answer the questions that follow.

i) If you decrease the wavelength of the light shining onto the metal, what happens to the voltage where the current goes to zero...


 * becomes a larger, negative number
 * becomes a smaller, negative number
 * is unchanged

ii) Which graph would represent an increase in the intensity?
 * E

iii) Which graph would represent an increase in wavelength to 290nm?
 * F <-- C

iv) Which graph would represent an increase in wavelength to 500 nm?
 * I

v) Which graph would represent a switch to sodium?
 * G

vi) What change or combination of changes would you need to explain the change observed in Graph H above? (check all that apply)

decrease in wavelength

increase in wavelength

decrease in intensity

increase in intensity


 * 1) If you have the experiment set up so that electrons are being emitted from the metal plate, which of the following are true and which are false?
 * 2) As long as conditions do not change, all emitted electrons have the same initial kinetic energy.
 * 3) False True
 * 4) The work function for the metal is different for different electrons.
 * 5) False True
 * 6) The energy of the photons hitting the plate must be less than the work function of the metal.
 * 7) False
 * 8) The electrons emitted with the largest initial kinetic energy are those that were the least tightly bound in the metal
 * 9) False


 * 1) You have a colored spot light, but you don't know its precise wavelength. To find out the wavelength you shine your light on a sodium target placed in a circuit as shown in the simulation. You look up the work function of sodium and find that it is 2.3 eV. If you set the battery voltage to -0.5 V, you find that the most energetic electrons nearly reach the right plate, but turn around just before they get there. What is the wavelength, in nm, of the colored light that you used? (You can answer this question either by doing a calculation or by using the simulation. To get practice for answering the next question, we recommend that you use both methods and check that they give the same answer.) SHOW YOUR WORK/EVIDENCE.

__Calculations__ __Data Tested in the simulator:__ NOTE: This is a picture of when a cluster of photoelectrons came close to the other end, but may not be at its closest, also no electrons made it across, and the batteries voltage could not be set at -0.5V so we set it at -0.6V causing the electrons to not reach as far.


 * 1) You have a plate of metal, but you have no idea what kind of metal it is. You come up with the brilliant idea of measuring the work function of this metal by using it as the target in a photoelectric effect experiment. You can perform this experiment virtually by selecting '???' as the target in the simulation. SHOW YOUR WORK/EVIDENCE.
 * 2) What is the work function, in eV, of the mystery metal?
 * 3) What is the mystery material?

To test this material and find its work function, we create an experiment with a set wavelength, as well as a set voltage, so that the photoelectrons just barely fall short of completing the circuit. In our experiment, we found the stopping voltage to equal -0.6V and the wavelength to equal 290 nanometers. With this information we can calculate the work force of this mystery material.

__Calculations:__

Experimental data: wavelength=290nm and Stopping Voltage=0.6V With the simulation, 0.45 V was the stopping potential for 299 nm. eVs=KEmax = hf - Ψ e(0.45) =(6.626 x 10-34 * 3x108 )/(1.6 x10-19 *299 x10-9)- Ψ e(0.45) = 4.155 - Ψ 3.7eV= Ψ

Based on the calculated value for work function, I believe that this mysterious metal is Selenium. The work function of Selenium is 5.11eV, while my experimental data and calculations gave me a work function value of 5.158eV. This metal is the closest to the value that I found, and is our mysterious metal ????. The closest metal to ???? is Magnesium with a work function of 3.68eV.

=** Part 3 **=
 * 1) The line on the graph of current to intensity can be described as ___linear with small positive slope__
 * 2) The line on the graph of energy to frequency can be described as __linear with high positive slope___
 * 3) At a __frequency below__ the frequency required to overcome the work function, increasing the light intensity causes the current to //increase / decrease / remain the same. //
 * 4) At a __frequency above__ the frequency required to overcome the work function, increasing the light intensity causes the current to // increase / decrease / remain the same.//
 * 5) Old darkrooms (for developing film) were once illuminated with a feint red light (765nm). If this was the limit of the silver compound used in the film, solve for the work function of the silver compound. _1.625__eV_____2.6*10__ __ -19 ___J




 * 1) Consider the following scenario: On a partly cloudy day you find that a household photovoltaic array outputs 2.4 amps of current. If the clouds part and the sun comes out, exactly doubling the amount of light incident on the PV array, we should expect the array to output //2.4 A / 4.8 A / more than 4.8 A / less than 2.4 A / between 2.4 and 4.8 A//.


 * 1) The work function for cesium is 1.96 eV. Find the cutoff wavelength for the metal. __634nm____m




 * 1) What is the maximum kinetic energy for the emitted electrons when 425 nm light is incident on #7’s metal? ___1.544*10__ __ -19 _____J




 * 1) In certain metal, the stopping potential is found to be 3.70 V. When 235 nm light is incident on the metal, electrons are emitted. What is the maximum kinetic energy given to the electrons in eV and J? ___ eV__ _ J



10.Stars vary in color. Which color indicates the hottest surface temperature of a star? 11.Which of the following objects, all moving at the same speed, would have a de Broglie wavelength associated with them that would be larger than that of a proton travelling a the same speed? 12.When green light shines upon a given metal, it emits phtoelectrons. Which of the following will also produce photoelectric emission, using this same metal? 13.Ultraviolet light shines upon a sheet of zinc metal, and photoelectrons are emitted. If the intensity of the light is increased, 14.Consider the following frequencies of electromagnetic radiation. Which photon has the greatest energy? 15.Compared to a photon of blue light, a photon of red light has 16.An electron is confined to a box of sides L and it has a definite speed. If the walls of the box were to move inward so that the box shrinks, the electron 17.The idea of packets or quanta of energy originated with 18.A matter wave 19.Which of the following does not demonstrate the wave nature of matter? 20.When doing the photoelectric effect experiment,
 * 1) Red
 * 2) Orange
 * 3) Yellow
 * 4) Blue
 * 1) An electron
 * 2) A neutron
 * 3) A bacteria
 * 4) A baseball
 * 1) Low intensity blue light
 * 2) Low intensity red light
 * 3) High intensity red light
 * 4) High intensity yellow light
 * 1) The electrons will have less energy.
 * 2) The electrons will have more energy
 * 3) More electrons will be emitted
 * 4) Fewer electrons will be emitted.
 * 1) 6.6 x 10-34 Hz
 * 2) 6.6 x 10-4 Hz
 * 3) 6.6 x 104 Hz
 * 4) 6.6 x 1018 Hz
 * 1) More energy
 * 2) Less energy
 * 3) Shorter wavelength
 * 4) The same wavelength
 * 1) Would speed up
 * 2) Would slow down
 * 3) Would move with the same speed
 * 4) Would exhibit none of the above.
 * 1) Louis de Broglie
 * 2) Max Planck
 * 3) Werner Heisenberg
 * 4) Erwin Schrodinger
 * 1) Applies only to “massless” particles
 * 2) Applies only to a photon
 * 3) Has a wavelength inversely related to its momentum
 * 4) Has a wavelength directly related to its momentum
 * 1) The cloud model of the electron
 * 2) The two slit interference pattern
 * 3) An electron in motion in a conducting wire (circuits)
 * 4) Electron diffraction
 * 1) What determines the amount of kinetic energy photoelectrons will have?
 * 2) The wavelength of the light, intensity of the light, and the work function of the metal.
 * 3) What determines the number of photoelectrons emitted from a metal?
 * 4) The number of photoelectrons emitted from a metal is determined by the intensity of the light that hits the metal and the work function of the metal.

=Virtual Lab=

Prelab Questions
> Solid sphere- John Dalton- Atom is a hard, solid sphere. > Plum-pudding- J.J. Thompson- Atom is mostly positive with negative “chips” inside of it, first person to come up with idea of positive and negative sub-particles. > Rutherford model- Ernest Rutherford- Positive part is concentrated nucleus yet most of it is empty space with negative electrons surrounding it. > Bohr model- Niels Bohr- Electrons are in different orbitals with different energy levels they move up an energy level when excited then go back down because they are unstable whilst excited. > Quantum model- Schröedinger- Electrons do not travel in orbitals; they only show where they are most likely to be.
 * 1) Recall from Chemistry, first learning about atomic models. You may look this information up in a textbook or online resource if you need to refresh your memory. Be sure to credit your source(s) appropriately.
 * 2) List the 6 models of the atom as they evolved chronologically.
 * 3) List the scientists who are credited with their discovery.
 * 4) Provide a brief description of each model, how it differs from the previous model, and any experiment done to derive the model.
 * Greek model- Leucippus and Democritus- Things are made of really small things that can no longer be broken down further.


 * Procedure: **

** Part 1: Models of the Atom **
// The different colored dots represent different colored light. The size and shape of the dots are not important, only the color. // // The big question mark represents a hydrogen atom. We know that it's hydrogen; it's the internal structure and the mechanisms for causing observed phenomena that we're unsure of. //
 * 1) Open the Java applet at PhET: [|Hydrogen Atom Model Applet] . The full address is [ [] .]
 * 2) Run the default simulation experiment by pressing the "on" button of the light source (which is a red button on the ray gun). Note that:

// You should have noticed by now that what goes in the "?" is not what always comes out. We can keep track of what's emitted by setting up a spectrometer to record emitted light. This is precisely what has been done in laboratory settings. //
 * 1) Check the "Show spectrometer" box to activate the spectrometer. What does the spectrometer show? What happens to the number of emitted light “counts” as more and more interactions occur?
 * The spectrometer shows which colors of light (or wavelengths) are absorbed and emitted by the atom of hydrogen. The amount of light emitted increases as more interactions occur; and light of different wavelengths are emitted as more interactions occur.
 * 1) Select the Billiard Ball model.
 * 2) Do you think it accurately represents what's been observed in laboratory settings?
 * No
 * 1) Why or why not?
 * The billiard Ball model does not represent what is observed in a laboratory because this model will reflect any type of light that strikes its surface. It is important to also note that this model is incorrect because the ball does not absorb or emit any photons. The laboratory model will absorb and emit certain wavelengths while all others pass through unfazed.
 * 1) Going in order from top to bottom, select the different models and observe interactions as predicted by each. [Note: for the deBroglie model, there are alternative views selectable from a drop down menu at the top of the applet.] For each model selected,
 * 2) Write down your impressions of how accurately the model predicts the actual behavior.
 * Billiard Ball model - This model is extremely incorrect and flawed for many reasons. The first is that in this model, the hydrogen atom reflects any photons that strike it, and does not interact with them in any way of absorption and emission. The second way that this model is flawed is that the billiard ball hydrogen atom does not allow any photons to pass through without 'bouncing' off the hydrogen atom's surface. In the experiment we see that most photons pass right through the atom without being touched, absorbed, or affected in any way.
 * Plum Pudding - This model is more accurate than the billiard ball model because it can absorb and emit photons of certain wavelengths and that some photons are able to pass through the atom without being affected. This model, however, is still incorrect because, as we see in the spectrometer, only one wavelength of photon is absorbed and emitted by the atom. This is because there are no energy level, so only one wavelength will cause the electron to move. Another flaw that we cannot really see in this lab is that the electron of a plum pudding model is not able to leave the atom and is stuck in the pudding.
 * Classical Solar System - This model is wrong simply because there is no way of stopping the electron from traveling into the proton nucleus. This causes the atom to destroy itself before the photons have a chance to reach the atom.
 * Bohr - Bohr's model is extremely close to the hydrogen that we see in the laboratory setup. The atom absorbs and emits photons of certain and varying wavelengths while allowing all other wavelengths to pass through without being affected. What makes this model incorrect, however, is that this model does not take into account the wave-like properties of the electron. The electron in this model does not have any wavelike properties.
 * DeBroglie - DeBroglie's model of the atom is extremely similar to the hydrogen atom observed in the laboratory. The only thing that makes this model incorrect is that it does not take into account the quantum number p, and the areas in which the electron can travel. In this model the electron wave is stuck in a specific orbital going around the proton. In the current model the orbital is more of a three dimensional area that the electron can travel.
 * Schrodinger - This model, from what we can see and know, is extremely accurate and acts the same as the experimental hydrogen atom.
 * 1) How is the overall appearance of the model different from the other(s) just seen?
 * Billiard Ball - This model is the only one that does not have a specific electron or proton. It is also the only model where the atom has no movement, and appears as a solid sphere.
 * Plum Pudding - This model is the only one which has an electron in the proton nucleus. This model is a positively charged material with electrons inside.
 * Classical Solar System - This model is the only one in which the movement of the electron is not limited by orbitals. As a result, the free traveling electron collides with the proton and destroys the atom. It is the first model in which the electron is not inside the atom's nucleus.
 * Bohr - This model is the same as the classical solar system, except that the electron's movement is limited by orbitals.
 * DeBroglie - This model is the same as the Bohr model, except that the electron is a wave that travels on the orbital.
 * Schrodinger - This model is the only one in which the electron has a three dimensional orbital where it can travel. These areas vary based upon the orbital that the electron is in. This model has wave like and particle like properties.
 * 1) Describe any differences in the interactions with incident light from the other models.
 * The Billiard ball is the only model in which photons are reflected and not absorbed, and all photons that hit the atom are redirected.
 * The plum pudding model is the only model in which only photons of one exact wavelength are absorbed and omitted while all others are not affected.
 * The classical solar system is the only one that never interacts with photons because it destroys itself before it has the chance.
 * The Bohr, DeBroglie, and Schrodinger models all interact the same way with photons of light. Certain photons are absorbed and emitted while all others are not affected.
 * 1) How do these models compare with other commonly known models? (i.e. rigid object of the Newtonian world, solar system like appearance, orbits, etc.)

** Part 2: Quantitative Analysis **
a) Does something //always// happen? What role does chance or probability play in these interactions? b) This model is for the hydrogen atom. How do you think things might change for more massive atoms? c)What are some shortcomings of each of these models?
 * 1) Run Schrodinger’s model. Turn the spectrometer on and activate the //energy level diagram//. Note the values in the bottom right corner of the experiment window.
 * 2) Look for patterns as the quantum state changes. When you see a transition occur on the energy level, press pause and record the quantum numbers of the transition and the wavelength of the photon emitted or absorbed.
 * n=2 l= 1 m= 0 and wavelength=100nm, frequency= 3 * 10 15 Hz.
 * n=2 l= 1 m= 1 and wavelength=100nm, frequency= 3*10 15 Hz.
 * n=6 l= 1 m= 1 and wavelength=92nm, frequency= 3.26*10 15 Hz.
 * n=5 l= 1 m= 1 and wavelength=92nm, frequency= 3.26*10 15 Hz.
 * n=3 l= 1 m= 0 and wavelength=650nm, freq= 4.615*10 14 Hz.-->n=2 l= 1 m= 0 and wavelength=100nm, freq= 3*10 15 Hz
 * n=6 l= 1 m= 1 and wavelength=410nm, freq= 7.317*10 14 Hz --> n=2 l= 1 m= 1 and wavelength=100nm, freq= 3*10 15 Hz
 * 1) Use the data you collected to calculate the photon energy and energy released/absorbed. (E=hf)
 * E=h( 3*10 15 Hz )= 12.42eV
 * E=h( 3*10 15 Hz )=12.42eV
 * E=h( 3.26*10 15 Hz )=13.496eV
 * E=h( 3.26*10 15 Hz )=13.496eV
 * E=h( 4.615*10 14 Hz )=1.911eV
 * E=h( 7.317*10 14 Hz )=3.029eV
 * 1) After you have collected the data, answer the following questions:
 * Something does not always happen, most particles pass the atom unaffected, while others are absorbed and emitted in other directions. This is based on probability as only certain photons are absorbed. This is because the photons that are absorbed are the exact amount of energy needed for the electron to jump energy levels.
 * More massive atoms, without complete outer electron shells, will give away their electrons with less energy because the outer electrons are farther away from the nucleus.
 * Each model has different shortcomings that inevitably cause inaccuracies. The billiard ball does not show the electrons and does not include them in any way. It is also important that the billiard ball redirects all of the photons, unlike the actual atom which redirects certain photons based on energy. The plum pudding model does not account for multiple energy levels. If this were the case, then there would be no way of determining which photons are absorbed and it would be random. Classical solar system model is incorrect because there is nothing to go against the attraction of the electron and protons, causing the electron to come into the nucleus and making the atom explode. The Bohr model goes against the uncertainty principle in which the electron is forced to follow a specific orbit. The DeBroglie model also violates the uncertainty principle in that we know the electrons orbit and direction of travel.

Follow-Up Questions
For questions involving the comparison of spectrometer outputs, the simulation should be set to the “fast” setting to save time (i.e. produce more comparable results in less time).

“Everything should be made as simple as possible, but not simpler.” a) What does he mean by this? Reflect back on what you’ve learned about models of the hydrogen atom in your science classes, how is this quote relevant? b) Imagine you are a physics teacher preparing for class for your students on the hydrogen atom. Is this quote still relevant? Explain your reasoning.
 * 1) Following is a quote from Albert Einstein:
 * This quote is relevant because it involves how closely we look at the atom. If we follow the billiard ball model, the atom is too simplified, reflecting photons that touch it and not including the electron. The DeBroglie model is too specific claiming that the electron travels in one specific orbit. It is better to simplify the DeBroglie model without over simplifying, such as with the billiard ball, by claiming the electron will probably be in an area of space, like the Schrodinger model.
 * Yes this quote is still relevant because the modern model of the atom is not perfectly accurate. As a result there is still work needed to be done to simplify the atom model without oversimplifying. This quote will always be relevant to modern physics.

a) Run Schrodinger’s model. Select the monochromatic checkbox. Set the slider to 103nm. Interactions will occur until eventually red light is emitted — then the interactions cease. Why is this? Explain your reasoning. [Hint: have the energy level diagram open and running while you run the simulation for this question.] b) Does the same thing happen with the Bohr and deBroglie models? What is the difference? c) Now set the slider to 122nm. Have the energy level diagram open and running while you run the simulation for this question. Interactions will occur indefinitely, but only for transitions between //n// = 1 and //n// = 2. Why is this? What fundamental property of modern physics accounts for this? List all of the possible quantum states of a hydrogen atom for these settings. (If you only list what you see in the bottom right corner of the experiment window you’ll miss one!).
 * 1) You will need to revisit the applet to answer this question.
 * The photons cause the electron to jump to and from the third energy level and the ground state. When the electron travels from the third state to the second state a red photon is emitted. The electrons stay in the second energy level because of teh quantum number l and the electrons must first return to the third level before it can go to ground state.
 * No, the interactions do not stop in the Bohr and DeBroglie models.
 * The energy of the photons are not enough to move the electron to a different energy level, and as a rule of the conservation of energy the electron does not jump to a higher energy level.

(n,l,m) (1,0,0) (2,1,1)