Question

The power dissipated in $3\Omega$ resistance in the following circuit is

• A. 0.75 W
• B. 0.25 W
• C. 1 W
• D. 0.5 W

Answer 1

Answer: (A)

The equivalent circuit of the given circuit will be

From circuit, $\frac{1}{R}=\frac{1}{3}+\frac{1}{6}$
$=\frac{2+1}{6}=\frac{3}{6}\Omega$
$R_1=2\Omega$

$R_2=R_2+R_2+R_4$
$=2+2+4=8\Omega$
The internal resistance of battery $=1\Omega$
So, the equivalent resistance of circuit
$=8\Omega +1\Omega$
$=9\Omega$
The current in the circuit
$I=\frac{V}{R}=\frac{45}{9}$
$=\frac{1}{2}A$
The power dissipated in $3\Omega$ resistance
$P=I^2\times R$
$={\left(\frac{1}{2}\right)}^2\times 3$
$=\frac{1}{4}\times 3$
$=0.75W$