Question

In a photocell, the photoelectrons emission takes place
A. After the \[{10^{ - 1}}\] second incident of light rays
B. After the \[{10^{ - 3}}\] second incident of light rays
C. After \[{10^{ - 6}}\] second on the incident of light rays
D. After the \[{10^{ - 8}}\] second incident of light rays

Answer 1

Hint: The photocells or photoelectric cells work based on the principle of the photoelectric effect. The main principle of the photocells is they convert the light energy into electrical energy and the application of the photocells is based on this principle. When light is incident on a metal surface, electrons are emitted known as photoelectrons. This phenomenon is called the photoelectric effect. The minimum frequency under which the emission of photoelectrons takes place is known as the threshold frequency.

Complete step by step solution:
When a photon of light is incident on a metal surface, the electrons present in the atom inside the metal gains some energy. By absorbing a certain amount of energy, these electrons get excited after a \[{10^{ - 8}}\] second from the time of incidence of light.

It takes this duration for this process to happen since the absorption of energy takes place inside the metal by the electrons. Therefore, the photoelectrons that are emitted take place after \[{10^{ - 8}}\] second incident of light rays.

Hence, Option D is the correct answer.

Additional information: If the electron emits from the surface of the metal, then the maximum kinetic energy of an electron is,
\[K.{E_{\max }} = E - W\]
Here, E is the energy of photons and W is the work function.

Note: There are three types of Photoelectric cells, they are photo-emissive cell, photovoltaic cell, and photo-conductive cell. Examples of photoelectric devices are Light-emitting diodes (LED), phototransistors, solar cells, etc.