Photocells and their Application

Photoemissive cell

A photocell converts the change in the intensity of light into a change in the electric current. The diagram shows a photocell circuit. The cathode is made of photosensitive material. A beam of light is allowed to fall on it. Anode is kept in front of the cathode and a battery is connected between the cathode and the anode as shown in the figure. The battery creates an electric field from anode to cathode. As the light falls on the cathode, photoelectrons are ejected out and are attracted by the anode. Thereby sending a current through the circuit that is measure by the galvanometer connected in the circuit. The current ranges of the order of microampere. This is how a photoemissive cell works.