Question

If power dissipated in the $9\Omega$ resistor in the circuit shown in $36\text{W}$, the potential difference across the $2\Omega$ resistor is

• A. $8\text{Volt}$
• B. $4\text{Volt}$
• C. $2\text{Volt}$
• D. $10\text{Volt}$

Answer 1

The correct option is D $10\text{Volt}$

Power dissipated across a resistor is $p=\frac{v^2}{R}$
Given Power dissipated across $9\Omega$ resistor is
$36=\frac{v^2}{9}$
$v=6\times 3=18\text{Volt}$
Current through $9\Omega$ resistor is $i_1=\frac{v}{9}=2\text{A}$
Current through $6\Omega$ resistor is $i_2=\frac{v}{6}=3\text{A}$

Current through $2\Omega$ resistor is $i=i_1+i_2=5\text{A}$
Potential across $2\Omega$ resistor is
$V_2=i\left(2\right)=5\times 2=10\text{V}$.