Summary

• Millikan oil drop experiment
• Blackbody radiation

• The photoelectric effect applet

• experiment another applet
• the cutoff frequency
• KE_max and intensity
• KE_max and frequency
• instant photoelectrons
• Einstein's theory
• quantized light
Example #3
Example #4
Example #5

• Example problem 3.36
• wave-particle duality info & graphs
• light particles paradox video

kw5
Light striking a clean metal produces photoelectrons. If the light is made twice as bright, what happens to the average kinetic energy of the photoelectrons?
A. The energy doubles.
B. The energy stays the same.
C. The energy is cut in half.
D. It's impossible to say.
Answer























kw5
Blue light shines on a metal, producing photoelectrons. When a red light is used the maximum KE of the photoelectrons
A. increases.
B. decreases.
C. stays the same.
D. Depends on the light intensity.
Answer























sj6 40.14
For a certain surface the emitted photoelectrons have v_max=460 km/s when l=625 nm. What minimum wavelength produces photoelectrons?
A. 756 nm
B. 897 nm
C. 962 nm
D. 1064 nm
Answer























 



B. The energy stays the same.
The average kinetic energy of the emitted photoelectrons depends only upon the frequency of the light. Making the light brighter produces more photoelectrons, but they have the same energy distribution as before.




























 



B. decreases.
Red light is composed of photons that have a lower frequency and thus less energy than blue photons. The emitted photoelectrons will therefore have less energy when red light is used.




























 



B. 897 nm