light dependent resistor viva question and answers

[Guest]

How conductivity varies with temperature and with resistance

[dhanabhagya]

Abstract

A light dependent resistor works on the principle of photo conductivity. Photo conductivity is an optical phenomenon in which the flow of material is increased when the light is absorbed by the material. When the light falls, when the photons fall on the device, the semiconductor material is excited for the electrons conductance band of the Verence Band. In light of the incident, the photon air force should be more in power than the band gap of semiconductor material to make the electrons jump from the band to the conduction band. Therefore, when there is sufficient energy speed on the device, then more and more electrons are excited for the band, resulting in large number of charging carriers. The result of this process is that when the circuit is closed, the device starts running as fast as the thorugh and it is said that the resistance of the device has decreased. This is the most common work principle of LDR