Question

A circuit operating at $\frac{360}{2\pi }$ Hz $\Omega$ contains a 1 F $\mu$ capacitor and a 20 resistor. The inductor must be added in series to make the phase angle for the circuit zero is

• A. 7.7 H
• B. 10 H
• C. 3.5 H
• D. 15 H

Answer 1

The correct option is A 7.7 H

To make phase angle zero, circuit should be purely resistive, so, reactance should be zero.

Hence, $X_L=X_C$

$wL=\frac{1}{\omega C}$

$L=\frac{1}{{\omega }^{2}C}$

$L=\frac{1}{(2\pi f{)}^{2}C}$

$L=\frac{1}{(2\pi \frac{360}{2\pi }{)}^2\times {10}^{-6}}$

$L=\frac{{10}^6}{129600}$

$L=7.7H$