Question

The frequency and the intensity of a beam of light falling on the surface of a photoelectric material are increased by a factor of two. This will :

• A. Increase the maximum kinetic energy of the photoelectrons by 2 and photoelectric current by a factor of 1 / 2
• B. Increase the maximum kinetic energy of the photoelectrons, and increase the photoelectric current by a factor of 2
• C. Increase the maximum kinetic energy of the photoelectrons by a factor of 2 and will have no effect on the magnitude of the photoelectric current produced
• D. Not produced any effect on the kinetic energy of the emitted electrons but will increase the photoelectric current by a factor of 2

Answer 1

The correct option is B Increase the maximum kinetic energy of the photoelectrons, and increase the photoelectric current by a factor of 2

Doubling the frequency will double the kinetic energy of the photo electron.

Since kinetic energy (E) is given by:

$E=h\nu -\varphi$, where $\varphi$ is the work function of the material.

Again the intensity of the light means the increase of number of incident photon on the surface. This will increase the number of ejected photon from the surface in proportionate manner.