Question

Calculate the heat dissipated in the circuit in 30 seconds.

• A. 30 J
• B. 45 J
• C. 75 J
• D. 125 J

Answer 1

The correct option is C 75 J

The two resistors are in series. So, the equivalent resistance is:
$R_{eq}=6\Omega +4\Omega$
$R_{eq}=10\Omega$

Power used is:
$P=\frac{V^2}{R_{eq}}$
$P=\frac{5^2}{10}=2.5W$

Energy consumed in 30 seconds is:
$E=Pt$
$E=2.5\times 30=75J$