Chapter 38, Problem 7A

To determine

The reason for the emission of the electrons from photosensitive surface due to violet light but not due to red light.

Explanation of Solution

Introduction:

The emission of the electrons from a photosensitive surface occurs due to increase in the energy of the electron in the surface. The energy of the light depends on the frequency of the incident light.

The frequency of the violet light is more than the frequency of the red light. So, the energy of the photon of the violet light is more than the photon of the red light. The electrons from the photosensitive surface occur due to falling of violet light on the photosensitive surface.

Conclusion:

The violet light ejects the electron from the photosensitive surface whereas red light has no effect on the surface because the frequency of the violet is more than the frequency of the red light.