Question

Explain the working of a diode as a half wave rectifier.

Answer 1

A circuit which rectifies half of the ac wave is called half wave rectifier.

The AC voltage $\left(V_S\right)$ to be rectified is obtained across the secondary ends $S_1{S}_2$ of the transformer. The $P$-end of the diode is connected to $S_1$ of the secondary coil of the transformer and $N$-end of the diode is connected to the other end $S_2$ of the secondary coil of the transformer through $R_L$. The rectified output voltage $V_{dc}$ appears across the load resistance $R_L$.

During the positive half cycle of the input ac input voltage, $S_1$ will be positive and the diode is forward biased and hence it conducts. So, current flows through the circuit and there is a voltage drop across $R_L$.

During the negative half cycle, $S_1$ will be negative and the diode $D$ is reverse biased and it does not conduct. No current flows through the circuit. So, voltage drop across $R_L$ will be zero.

Hence, no output voltage is obtained. Thus, unidirectional pulsating output is obtained.

The ratio of dc power output to the ac power input is known as rectifier efficiency.

Efficiency of half wave rectifier is $40.6$%.