Question

Find the power dissipation in resistance $12\Omega$ in circuit shown above figure.

• A. 27 W
• B. 20 W
• C. 50 W
• D. 100 W

Answer 1

The correct option is A 27 W

Given : $V=60$ volts

Equivalent resistance between A and B $R_{AB}=12\parallel 6\parallel (7+5)=12\parallel 6\parallel 12$

$\therefore$ $\frac{1}{R_{AB}}=\frac{1}{12}+\frac{1}{6}+\frac{1}{12}$

$⟹R_{AB}=3\Omega$

Voltage between A and B $V_{AB}=\frac{3}{3+7}V=\frac{3}{10}\times 60=18$ volts

$⟹$ Voltage across 12 $\Omega$ resistance $V^{\prime }=V_{AB}=18$ volts

$\therefore$ Power dissipated in 12 $\Omega$, $P=\frac{{18}^2}{12}=27$ W