Question

An AC signal of $50\,Hz$ frequency is input of a full wave rectifier using two diodes. What is the output frequency after full wave rectification?
A. $25\,Hz$
B. $50\,Hz$
C. $100\,Hz$
D. $200\,Hz$

Answer 1

To solve this question we have to first understand what full wave rectification is and how does frequency affect full wave rectification.
Full wave rectification rectifies the input voltage negative portion to a positive voltage, then transforms it using a diode bridge configuration into DC (pulse current). Afterwards, by charging or discharging a capacitor, the waveform is made smooth, resulting in a clean DC signal.
In a full wave rectifier, frequency is determined by how much time period is completed in one second.

Complete step by step solution:
Two power diodes attached to a single load resistance $RL$ are the complete wave rectifier circuit, with each diode taking it in turn to supply the load resistor with current. The first diode conducts in the forward direction when the first point of the transformer is positive. The second diode conducts in the forward direction when the second point of the transformer is positive in the negative half of the cycle.
The input frequency is doubled during full wave rectification. And in the AC input signal, all the negative components are converted into positive components. The positive components are then doubled.

So, when the input frequency is $50\,Hz$, the output frequencies will double that of the input frequency.
Hence, the output frequency will be $100\,Hz$ .

Therefore, option C is correct.

Note: So, in short we can say that in a full wave rectifier, a cycle twice as quick as the input frequency is completed by the output signal. This is because symmetrical, half-positive and half-negative are the input waves. The positive components double the rendering of all the negative components into positive ones.