Photo emissive cell:
Its working depends on the electron emission from a metal cathode due to irradiation of light or other radiations.
- It consists of an evacuated glass or quartz bulb in which two metallic electrodes – that is, a cathode and an anode are fixed.
- The cathode C is semi-cylindrical in shape and is coated with a photo sensitive material. The anode A is a thin rod or wire kept along the axis of the semi-cylindrical cathode.
- A potential difference is applied between the anode and the cathode through a galvanometer G.
Working:
- When cathode is illuminated, electrons are emitted from it. These electrons are attracted by anode and hence a current is produced which is measured by the galvanometer
- For a given cathode, the magnitude of the current depends on the intensity to incident radiation and the potential difference between anode and cathode.
