SOLUTION

The thyristor is also called a silicon-controlled rectifier (SCR), is basically a four-layer three-junction p-n-p-n device. It has three terminals: anode, cathode, and gate. It is basically an electronic switching device that can remain in conducting (on) and nonconducting (OPI:) state. However, it is a unidirectional device and can conduct only in one direction like a diode. The switching state of the device can be controlled by one of its terminals.

The thyristor has three terminals. The terminal connected to the end p-region is called the anode (A), the terminal connected to the end n-region is called cathode (K) and the terminal connected to the middle p-region is called gate (G). The thyristor is manufactured by diffusing four layers of impurities (p and n-type) into a silicon wafer of suitable thickness. The whole assembly of the thyristor is mounted on a heat sink with the help of a thread. The purpose of the heat sink is to dissipate the heat generated in the thyristor.