Photo Emissive Cell

Photo Emissive Cell:

The photo emissive cell consists of a glass envelope with a vacuum inside.

The envelope also contains a light sensitive cathode and an anode.

When light strikes on a photo emissive cell, the radiation causes the cathode negative electrons to be emitted which are attracted by the positive anode and a current to flow (photoelectric effect).

The value of this current is proportional to the intensity of light falling on the cathode.

Diode

Diode:
The term “diode” is customarily reserved for small signal devices, I ≤ 1 A. The term “rectifier” is used for power devices, I > 1 A.











The diode is the earliest and simplest type of electronic valve having two active terminals, an anode and a cathode (p-n junction), used in circuits for converting alternating current to direct current. It was formerly widely used as a rectifier and detector but has now been replaced in most electrical circuits by the more efficient and reliable semiconductor diode.