Chapter 38, Problem 24A

To determine

The reason for no ejection of electrons from the photosensitive surface by the red light.

Explanation of Solution

Introduction:

The ejection of the electron from any surface occurs if the energy of the photons of the incident light is greater than or equal to the work function of the surface. The work function of any metal is the minimum energy to excite an electron for ejection from the metal surface.

The ejection of the electron from photosensitive material occurs if the energy per photon of the incident light is greater than the work function or energy barrier of the photosensitive material. The energy per photon of the red light is less than the energy per photon of the dim source of the blue light. So, the electron does not eject from the photosensitive material due to incidence of the red light on the photosensitive material.

Conclusion:

The red light has no effect on the ejecting electrons from the photosensitive material due to the less energy per photon than the less energy per photon of the blue light.