Which phenomena can be explained by using the particle nature of light?

Show that wave theory cannot explain fundamental characteristics of photoelectric effect.

$A$ source of variable potential difference is connected across a photoelectric cell, and the photoelectric current is plotted against the applied potential difference. The graph with the broken line represents the initial curve of current versus applied potential difference. If the frequency of the incident light is increased and its intensity is reduced, which curve now represents the situation?

In the photoelectric effect, keeping the frequency of incident radiation and the accelerating potential fixed, if the intensity of incident light is increased,

$A$ small metal ball is suspended in a uniform electric field with the help of an insulated thread. If a high energy $X-$ray beam falls on the ball,then the ball

Photoelectric effect occurs when ultraviolet rays are incident on a metal plate. It does not occur when which of the following are incident?