Light is shone on a metal and photoelectrons are emitted.

Question

Can you tell me the three things from the list below which might cause the photoelectron emission to stop.

Decreasing the intensity of the light
Increasing the frequency of the light
Decreasing the wavelength of the light
Increasing the wavelength of the light
Changing the metal
Decreasing the frequency of the light
Increasing the intensity of the light

thx trigger

Answer 1

Assistance needed.

Answer 2

The emission work function varies by type of metal. Photons must have sufficent energy, above the threshold energy (energy=constant*frequency). So reducing the frequency reduces the energy available to the photons, and at cuttoff, they cease. Long wavelengths is the same thing.