Which of the following statements about photoelectrons is correct?

A. A faint green light produces photoelectrons with less kinetic energy than a bright red light
B. A red light releases a smaller number of electrons than a green light
C. A faint green light produces photoelectrons with greater kinetic energy than a bright red light
D. A red light produces more photoelectrons than a green light

Correct Answer:

Option B – A red light releases a smaller number of electrons than a green light

Explanation

When the light strikes the metal, its energy is transferred to the electrons. Different wavelengths (or colours) of light carry different amounts energy. If the light has a high enough energy, the electrons will escape from the surface of the material. If the energy of the light is too low, then it will not.

Thus, there is a threshold of energy needed for the metal to lose an electron, and this threshold is different for different materials. The photon of blue light has higher energy as compared to red light; so blue light emits electrons of greater kinetic energy than that of red light.