In the half wave rectifier circuit operating from $50\,Hz$ main frequency, the fundamental frequency in the ripple would be:
(A) $25\,Hz$
(B) $50\,Hz$
(C) $70.7\,Hz$
(D) $100\,Hz$

Hint: A half wave rectifier is the type of rectifier that allows only the one-half cycle of the AC voltage to pass and it blocks the other half cycle. It allows only positive wave forms and blocks the negative forms. Half wave rectifier helps to convert the AC voltage to DC voltage.

Complete step by step solution:
A rectifier is the electrical device which is used to convert the AC voltage to the DC voltage. The conversion of the AC voltage to the DC voltage is done by using the single diode or the group of diodes. In a half wave rectifier, it uses only one diode to convert the AC voltage to the DC voltage. In the half wave rectifier, the main advantage is that the half wave rectifier allows the current to flow in only one direction. Half wave rectifier is the very simplest form of the rectifier.

When the alternating current is passed in the half wave rectifier, in alternating current it has both positive and negative wave forms but the half wave rectifier allows only one half either positive or negative. The half wave rectifier changes the current only, it will not change the frequency of the input signals. So, in the half wave rectifier the input frequency of the input signal is the same to the output frequency of the output signal.

So, the fundamental frequency in the ripple would be the same as the main frequency or the input frequency.

Hence, the option (B) is the correct answer.

Note: The input frequency of the input signal is the same as the output frequency of the output signal in the Half wave rectifier, but in the full wave rectifier the output frequency of the output signal is twice the input frequency of the input signal.