The work functions of Caesium $(Cs)$, Potassium $(K)$, and Sodium $(Na)$ are $2.14\,eV$, $2.30\,eV$, and $2.75\,eV$ respectively. If incident electromagnetic radiation has an incident energy of $2.20\,eV$, which of these photosensitive surfaces may emit photoelectrons?

Threshold frequency of which of the following metals does not lie in the ultraviolet region (in the case of the photoelectric effect)?

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?

Why is photoelectric current proportional to intensity?

In the photoelectric effect,the photocurrent: