Question

Explain with the help of a circuit diagram the working of a photo diode. Write briefly how it is used to detect the optical signals.

Answer 1

A junction diode made from light sensitive semiconductor is called a photodiode
An electrical device that is used to detect and convert light into an energy signal with use of photo detector is Know as a photodiode. The light that falls on it controls the function of pn-junction.Suppose the wavelength is such that the energy of a photon $\frac{h\nu }{\lambda }$ is enough to break a valance bond. There is an increase in number of charge carriers and hence the conductivity of the junction also increase. New bole-electron pairs are created when such light falls on the junction. if the junction is connected in a circular, the intensity of the incident light controls the current in the circuit.