Question

A coil of 0.01 H inductance and $1\Omega$ resistance is connected to 200 V, 50 Hz ac supply. The time lag between maximum alternating voltage and current is

• A. $\frac{1}{250}s$
• B. $\ \frac{1}{300}s$
• C. $\frac{1}{200}s$
• D. $\frac{1}{350}s$

Answer 1

Answer: (A)

$\frac{1}{250}s$

Answer 2

: Here, , $L = 0.01H,R = 1\Omega$

$V_{rms} = 220V,\upsilon = 50Hz$

As ,$\tan\varphi = \frac{X_{L}}{R} = \frac{\omega L}{R} = \frac{2\pi\upsilon L}{R}$

$\tan\varphi\frac{2 \times 3.14 \times 50 \times 0.01}{1} = 3.14\therefore\varphi = \tan^{- 1}(3.14)$

$= 72^{o} = 72^{o} \times \frac{\pi}{180}rad$

The time lag between maximum alternating voltage and current is.

$\Delta t = \frac{\varphi}{\omega} = \frac{\frac{72 \times \pi}{180}}{2\pi \times 50} = \frac{1}{250}s$