Question

An electronic voltmeter consisting of a full wave precision rectifier and an average circuit gives correct R.M.S value for square wave inputs. It's reading for a 2 V peak to peak sinusoidal input will be

• A. $\frac{2}{\pi }V$
• B. $\frac{1}{\pi }V$
• C. $\frac{2}{\sqrt{2\pi }}V$
• D. $\frac{\sqrt{2}}{\pi }V$

Answer 1

The correct option is A $\frac{2}{\pi }V$

Given,

$(V_{pp}{)}_{input}=2V$

$\Rightarrow (V_p{)}_{input}=\frac{2}{2}=1V$

For full wave rectifier

$(V_{dc}{)}_{output}=\frac{2}{\pi }(V_p{)}_{input}$

$=\frac{2}{\pi }\times 1=\frac{2}{\pi }V$

Now,
$V_{out}=\left(\text{Form Factor of Square wave}\right)\times \frac{2}{\pi }$

$=1\times \frac{2}{\pi }=\frac{2}{\pi }V$