Question

Using an A.C. voltmeter the potential difference in the electrical line in a house is read to be 234 volts. If the line frequency is known to be 50 cycles/second, the equation for the line voltage is

• A. $V=165sin\left(100\pi t\right)$
• B. $V=331sin\left(100\pi t\right)$
• C. $V=220sin\left(100\pi t\right)$
• D. $V=420sin\left(100\pi t\right)$

Answer 1

The correct option is B $V=331sin\left(100\pi t\right)$

So, rms voltage is $234V$

then peak voltage is $234\times \sqrt{2}$

$=331V.$

Frequency is 50 cycles/second

So, $w=2\pi f$

$=2\pi 50$

$=100\pi$

So, $V=V_{m}sinwt$

$=331sin\left(100\pi t\right)$.