Question

A current of $3$ amp. flows through the $2\Omega$ resistor shown in the circuit. The power dissipated in the $5\Omega$ resistor is

• A. 1 watt
• B. 5 watt
• C. 4 watt
• D. 2 watt

Answer 1

Answer: (B)

$2\Omega ,4\Omega$ and $(1\Omega +5\Omega )$ are in parallel.
So potential difference is the same.
$V=2\Omega \cdot i_1=4\Omega \cdot i_2=6\Omega \cdot i_3$
$2\cdot 3=6\Omega \cdot i_3\Rightarrow i_3=1amp$.
Total P.D. $=5\times 1+1\times 1=6V$.
$\therefore$ Power dissipated in $5\Omega$ resistance $=\frac{V^{\prime 2}}{R}$
where $V^{\prime }$ is the P.D. across $5\Omega =5V$.
$\therefore$ Power $=\frac{25V^2}{5\Omega }=5$ watt