Question

As given in the figure, a series circuit connected across $200V,60Hz$ line consists of a capacitor of capacitive reactance $30\Omega$, a non-inductive resistor of $44\Omega$, and a coil of inductive reactance $90\Omega$ and resistance $36\Omega$. The power dissipated in the coil is

• A. 320 W
• B. 176 W
• C. 144 W
• D. 0 W

Answer 1

Answer: (C)

Impedance of the circuit, $Z=\sqrt{{\left(R_1+R_2\right)}^2+{\left(X_L-X_C\right)}^2}$
$=\sqrt{(44+36{)}^2+(90-30{)}^2}=\sqrt{(80{)}^2+(60{)}^2}=100\Omega$
Current in the circuit, $I=\frac{V}{Z}=\frac{200V}{100\Omega }=2A$
Power dissipated in the coil $=I^2{R}_2=(2A{)}^2(36\Omega )=144W$