Question

In a photo electric experiment, when intensity of incident light increases :

• A. photo-current increases
• B. photo-current decreases
• C. kinetic energy of emitted photoelectrons increases
• D. kinetic energy of emitted photoelectrons decreases

Answer 1

The correct option is A photo-current increases

According to Einstein's theory of phototelectric effect a single incident photon ejects a single electron. Therefore, when intensity increases, the number of incident photons increases, so number of ejected electrons increases, hence, photocurrent increases
Now, maximum energy of electron $=\frac{1}{2}m{v}_{max}^2$
and $\frac{1}{2}m{v}_{max}^2=e{V}_0$, where $V_0$ is stopping potential.
Thus, the maximum kinetic energy of the electrons does not depend upon the intensity of the incident rays, because the stopping potential is not affected by the increase of the intensity of rays.