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Quantum Physics – The Double-Slit Experiment
1. What happens to the interference patterns created in the electron double-slit
experiment when detectors are used to determine which slit an electron is passing
through? How do researchers explain this?
2. When the electrons are observed, what interpretations do researchers suggest causes
the electrons to travel the way they do? Which interpretation do you think is true and
why?
Quantum Physics – The Photoelectric Effect
1. Which of the coloured lights (red, orange, blue) on a Christmas tree emits photons
with the most and least energy? Explain.
2. Does your stove emit energy when the burner is not turned on? Explain.
3. A single photon is ejected from a light source with a frequency of 2.0 x 1014 Hz. How
much energy does it possess?
4. What is the maximum kinetic energy of a photoelectron that has been liberated
from a platinum metal surface by a photon that has a frequency of 3.13 x 1015 Hz?
5. The maximum kinetic energy of electrons emitted form a metal surface is 3.65 x 10-19
J when photons with a frequency of 1.25 x 10 15 Hz strike the surface. What is the most
likely type of metal surface that the photons are striking?
Quantum Physics – The Double-Slit Experiment
1. What happens to the interference patterns created in the electron double-slit
experiment when detectors are used to determine which slit an electron is passing
through? How do researchers explain this?
2. When the electrons are observed, what interpretations do researchers suggest causes
the electrons to travel the way they do? Which interpretation do you think is true and
why?
Quantum Physics – The Photoelectric Effect
1. Which of the coloured lights (red, orange, blue) on a Christmas tree emits photons
with the most and least energy? Explain.
2. Does your stove emit energy when the burner is not turned on? Explain.
3. A single photon is ejected from a light source with a frequency of 2.0 x 1014 Hz. How
much energy does it possess?
4. What is the maximum kinetic energy of a photoelectron that has been liberated
from a platinum metal surface by a photon that has a frequency of 3.13 x 1015 Hz?
5. The maximum kinetic energy of electrons emitted form a metal surface is 3.65 x 10-19
J when photons with a frequency of 1.25 x 10 15 Hz strike the surface. What is the most
likely type of metal surface that the photons are striking?
Answers: Double Slit
1. The interference pattern goes away once it is observed. The electrons act like
particles instead of waves, as previously seen. Researchers suggest that the
observation disturbs the electrons and changes the “reality”.
2. Interpretations: Collapse (electron wave collapses to a particle), Many Worlds
(electrons choose one slit to go through but there is another world where the
electron chooses another slit to go through), Copenhagen (smoke and mirrorsdon’t worry about what happens between the slits and the screen just worry about
the math!), Pilot Wave (the electron particle follows an invisible wave “path”).
Photoelectric Effect
1. The red light has less energy and a smaller frequency according to the visible light
spectrum. The green light has more energy than red but less than blue. Blue
would be the “hottest” or have the most energy.
2. The stove emits energy but not enough for the radiation to be visible to us. Not
on the visible spectrum. When it is turned on it turns red, the lowest energy light
that we can see.
3. E = hf
E = (6.626*10-34)(2.0 x 1014)
E = 1.3 x 10-19 J
4. What is the maximum kinetic energy of a photoelectron that has been liberated
from a silver metal surface by a photon that has a frequency of 3.13 x 1015 Hz?
Change eV to J:
 1.60 x 10 -19
5.65eV 
1eV

J
  9.04 x10 19

E k (max)  hf  W
E k (max)  6.625 x10 34 (3.13x1015 )  9.04 x10 19
E k (max)  2.0736 x10 18  9.04 x10 19
E k (max)  1.17 x10 18 J
5. 2.90 eV so Lithium