Question

What will be the self-inductance of a coil to be connected in a series with a resistance of $\pi \sqrt{3} \,\Omega$ such that the phase difference between the e.m.f. and the current at $50 \,Hz$ frequency is $30^{\circ}$ ?

• A. 0.5 H
• B. 0.03 H
• C. 0.05 H
• D. 0.01 H

Answer 1

Answer: (D)

$\tan \phi=\frac{X_{L}}{R}=\frac{2 \pi v L}{R}$
$\Rightarrow \tan 30^{\circ}=\frac{2 \pi \times 50 \times L}{\pi \sqrt{3}}$
$ \Rightarrow L=0.01\, H$