Question

Which one of the following is true in photoelectric emission

• A. Photoelectric current is directly proportional to the amplitude of light of given frequency
• B. Photoelectric current is directly proportional to the intensity of light of given frequency at moderate intensities
• C. Above the threshold frequency the maximum kinetic energy of photoelectrons is inversely proportional to the frequency of incident light
• D. The threshold frequency depends on the intensity of incident light

Answer 1

Answer: (B)

Photoelectric current is directly proportional to the intensity of light of given frequency at moderate intensities

For photoelectric effect frequency of the incident light should be greater than the threshold frequency of the metal. Photoelectric current is directly proportional to the square of the amplitude of light.
Maximum kinetic energy of photoelectrons $=h\nu -\varphi$
where, h is planks constant.
$\nu$ is frequency of incident light
$\varphi$ is work function of metal.
Threshold frequency is property of the material not of intensity of incident light.
Current is directly proportional to the intensity of light.