Photoelectric Effect
____
1. Which occurs when an opaque object with a temperature above absolute zero emits
photons?
a. black-body radiation
b. Compton effect
c. photoelectric effect
d. UV catastrophe
____
2. Which best describes Einstein’s explanation of the photoelectric effect?
a.
b.
c.
d.
____
Light energy is concentrated in distinct “packets”.
Light energy is evenly distributed over the entire wave front.
Metallic surfaces always absorb electrons when illuminated.
Metallic surfaces always emit electrons when illuminated.
3. If light is incident on a metal surface, which property of light will determine if electrons will be emitted?
a.
b.
c.
d.
amplitude
frequency
intensity
wavelength
____
4. When light of frequency 8.6 × 1014 Hz is incident on a metal surface, the maximum kinetic energy of the
photoelectrons is 0.500 eV. What is the work function of the metal?
a. 0.50 eV
b. 3.1 eV
c. 3.5 eV
d. 4.1 eV
____
5. What is the stopping potential for an ejected photoelectron that has 3.40 x 10-19 J of kinetic energy?
a. 0.471 V
b. 2.13 V
c. 3.40 V
d. 5.44 V
____
6. If an electron has a speed of 1.0 × 104 m/s, what potential difference must be applied to stop the electron?
a. 4.6 × 10-23 V
c. 2.8 × 10-4V
b. 8.4 × 10-20 V
d. 5.2 × 10-1 V
____
7. Blue light is shone on a metal surface and electrons are ejected at a given rate and with a certain amount of
energy. If the intensity of the blue light is increased, which describes the rate (current) and the energy per
electron of the ejected electrons?
a.
b.
c.
d.
____
Rate
decreases
increases
constant
constant
8. If the wavelength of light is 250 nm, what is the maximum kinetic energy of the photoelectrons in a metal
that has a work function of 4.5 eV?
a. 0 eV
b. 0.37 eV
____
Energy per Electron
constant
constant
decreases
increases
c. 0.47 eV
d. 0.53 eV
9. If the stopping potential of a photoelectric cell is 5.60 V, what is the maximum kinetic energy of the
photoelectrons emitted?
a. 2.90 × 10-20 J
b. 8.96 × 10-19 J
c. 5.60 × 101 J
d. 3.50 × 1019 J
____ 10. A metal with a work function of 4.56 eV is illuminated by light with a wavelength of
1.7 x 10-7 m. What is the maximum kinetic energy of the emitted photoelectrons?
a. 4.4 × 10-19 J
b. 7.3 × 10-19 J
c. 1.9 × 10-18 J
d. 1.5 × 10-18 J
____ 11. Light of a particular wavelength is incident on a metal surface. If electrons are emitted
from this surface, what situation would result in more electrons per unit time with less
kinetic energy per electron?
a.
b.
c.
d.
Intensity
decrease
decrease
increase
increase
Wavelength
decrease
increase
decrease
increase
12. Calculate the maximum wavelength that will cause photoelectric emission from
a metal surface having a work function of 2.00 eV.
13. The photocell in a movie projector contains sodium, which has a work function (Wo) of
2.28 eV. Explain, using calculations, why the photoelectric effect does not occur when
the photocell is illuminated by a light with λ = 650 nm.
14. A metal surface has a work function of 4.20 eV. What is the kinetic energy, in
joules, of the emitted electrons if the wavelength of light is 250 nm?
15. An emitted photon of 122 nm hits a photocell, causing the photoelectric effect. If
the work function of the metal is 3.68 × 10-19 J, what is the maximum kinetic
energy of the emitted electron?
16. A 2.72 x 1015 Hz photon acquires 1.1 x 10-18 J of kinetic energy. What is the work function of the metal?
17. If the work function of silver is 3.83 eV, what is the longest wavelength of sunlight that can eject an
electron from a silver surface?
18. A material with a work function of 5.15 eV is shone with incident light that has a wavelength
of 632 nm.
a) Determine whether this light will cause the metal to exhibit the photoelectric effect. Show
workings.
b) If the emitting metal is changed, the threshold wavelength in the photoelectric effect
increases. Explain how the work function value will change. (1 mark)
19. In a photoelectric effect experiment, light was shone on a metal surface and the
data below were recorded.
i) Graph these results, including the line of best fit.
ii) Use the graph to determine the work function for this metal surface.
20. In a photoelectric effect experiment, light is shone on a metal surface. The graph
below illustrates the maximum kinetic energy of ejected electrons versus frequency of the incident light of
the photons.
(i) Use the graph to determine a frequency at which the photoelectric effect will not occur,
and explain why it will not occur.
(ii) Determine the work function of the metal.
21. When a light bulb in a movie projector is replaced with a bulb that has the same intensity but different
frequency, the sound does not work. With reference to the photoelectric effect, explain why this occurs.
Photoelectric Effect
Answer Section
MULTIPLE CHOICE
1.
4.
7.
10.
ANS:
ANS:
ANS:
ANS:
A
B
D
A
PROBLEM
12. ANS:
13. ANS:
14. ANS:
15. ANS: 1.26 10-18 J
2.
5.
8.
11.
ANS:
ANS:
ANS:
ANS:
A
B
C
D
3.
6.
9.
ANS: B
ANS: C
ANS: B
16. ANS:
17. ANS:
18. ANS:
19. ANS:
i)
ii)
20. ANS:
21. ANS:
In order for the photoelectric effect to occur, the energy of the incident photons must
be greater than the work function of the metal. 0.5 marks
Changing the frequency will change the energy of the incident photons so that in this
case, no electrons are ejected from the metal. 1 mark
No electrons = no current = no sound. 0.5 marks
DIF:
iii
TOP: Photoelectric effect
KEY: Physics of Movie sound STSE