Question

A generator produces a voltage that is given by $V=240\sin 120t$ Volt, where $t$ is in second. The frequency and r.m.s. voltage are

• A. $60Hz$ and $240V$
• B. $19Hz$ and $120V$
• C. $19Hz$ and $170V$
• D. $754Hz$ and $170V$

Answer 1

Answer: (C)

$19Hz$ and $170V$

It is given $V=240\sin 120t$

So, $V_{max}=240$

then $V_{rms}=\frac{V_{max}}{\sqrt{2}}$

$V_{rms}=\frac{240}{\sqrt{2}}$

$=170V$

and $\omega =120$

frequency = $\frac{w}{2\pi }=\frac{120}{2\pi }=\frac{60}{\pi }=19Hz$