Question

The peak power consumed by a resistive coil, when connected to an AC source, is 80 W. Find the energy consumed by the coil in 100 seconds, which is many times larger than the time period of the source.

Answer 1

Peak power of the resistive coil, $P_0=80\mathrm{W}$
Time, t = 100 s
RMS value of power $\left(P_{rms}\right)$ is given by,
$P_{\mathrm{rms}}=\frac{P_0}{2}$,
where P₀ = Peak value of power
$\therefore P_{\mathrm{rms}}=\frac{P_0}{2}=40\mathrm{W}$
Energy consumed $\left(E\right)$ is given by,
E = P_rms × t
= 40 × 100
= 4000 J = 4.0 kJ