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.
$V=2 \,\Omega \cdot i_{1}=4 \Omega \cdot i_{2}=6 \,\Omega \cdot i_{3}$
$2 \cdot 3=6 \Omega \cdot i_{3} \Rightarrow i_{3}=1 amp$.
Total P.D. $=5 \times 1+1 \times 1=6 V$.
$\therefore$ Power dissipated in $5 \Omega$ resistance $=\frac{V^{\prime 2}}{R}$
where $V'$ is the P.D. across $5 \Omega=5 V$.
$\therefore$ Power $=\frac{25 V^{2}}{5 \Omega}=5$ watt