(a) Explain the characteristics of a $p-n$ junction diode that makes it suitable for its use as a rectifier.

(b) With the help of a circuit diagram, explain the working of a full wave rectifier.

Explain the following, giving reasons:

(a) A doped semiconductor is electrically neutral.

(b) In a $p$ - $n$ junction under equilibrium, there is no net current.

(c) In a diode, the reverse current is practically not dependent on the applied voltage.