Question

Explain the working of photoemissive cells. Write any two applications of photoelectric cells.

Answer 1

Step 1: Working of photoemissive cells,

1. A photoemissive cell works on the principle of einstein's photoelectric effect.
2. The photoelectric effect is a phenomenon that occurs when the photon particle from a light ray is incident on a metallic plate, the photon particles impart energy to the free electrons present on the surface of the metallic plate or the emitter.
3. When these energetic electrons leave the surface of the emitter and start flowing inside the conductor towards the collector.
4. This results in the generation of a current which is known as photoelectric current.
5. In a photoemissive cell, vacuum cells and gas-filled cells are used.
6. Using these laws of photoelectricity, a photocurrent is generated.

Step 2: Application of photo emissive cells

Few applications of a photoemissive cell are:

1. Burglar alarm
2. Automated door system
3. In motion pictures for the production of sound