Light striking a metal surface causes electrons to be emitted from the metal via the photoelectric effect.?

Question

In a particular experiment to study the photoelectric effect, the frequency of the incident light and the temperature of the metal are held constant. Assuming that the light incident on the metal surface causes electrons to be ejected from the metal, what happens if the intensity of the incident light is increased?

A. The work function of the metal decreases.
B. The number of electrons emitted from the metal per second increases.
C. The maximum speed of the emitted electrons increases.
D. The stopping potential increases.

Enter the letter(s) corresponding to the correct answer(s) in alphabetical order. For example, if you think that choices A and C are correct, enter AC.

In another experiment, the intensity of the incident light and the temperature of the metal are held constant. Assuming that the initial light incident on the metal surface causes electrons to be ejected from the metal, what happens if the frequency of the incident light is increased?

A. The work function of the metal increases.
B. The number of electrons emitted from the metal per second decreases.
C. The maximum speed of the emitted electrons increases.
.D The stopping potential increases.

Enter the letter(s) corresponding to the correct answer(s) in alphabetical order. For example, if you think that choices A and C are correct, enter AC.

Answer 1

The energy of the electron emitted is

1/2mv^2 = hf -Wf

where m = mass of electron, v = speed of electron, Wf =work funciton of metal,
h =planck's constant, and f=frequency of light.

If frequency is fixed, the energy of teh light is ifxed. The work function is fixed since temperature is constant. So the only correct answer is B - the number emitted increases er second. More intensity means more photons/second hitting the metal. Each photon has energy hf and so the kinetic energy of the electron ejected cannot change.

Answer 2

B

Answer 3

B.