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In the given circuit, the average power dissipated in 6Ω resistor is :

A source V = 12 sin(377t) connected in a loop with current i and a 6 ohm resistor

  • A.4 Watt
  • B.12 Watt
  • C.14 Watt
  • D.16 Watt

Answer: B

The average power is 12 W.

The source has a peak value of 12 V, and average power in a resistor depends on the rms value, \(P = V_{rms}^{2}/R\). For a pure resistor the frequency (377 rad/s, that is 60 Hz) does not matter.

\[ \begin{aligned} V_{rms} &= \frac{12}{\sqrt{2}} \\ P &= \frac{V_{rms}^{2}}{R} = \frac{144/2}{6} = 12\ \text{W} \end{aligned} \]

Using the peak value in place of the rms value gives 144/6 = 24 W, which is twice the true average. 4 W, 14 W and 16 W do not follow from the circuit.

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