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Concepts Of Physics MCQ Edition [Volume 2]PhysicsAlternating Current

A circuit is supplied with a current of 10 A (rms) by an AC source rated at 100 V (rms). The average power delivered by the source

Options

  1. Acan be exactly 1000 W
  2. Bcan be less than 1000 W
  3. Ccan be greater than 1000 W
  4. Dmust be exactly 1000 W

Correct answer

B. can be less than 1000 W

Step-by-step solution

The average power delivered by an AC source is given by P_ avg = V_ rms I_ rms , where is the power factor of the circuit. Given V_ rms = 100 V and I_ rms = 10 A , we have P_ avg = 100 10 = 1000 W . Since the power factor satisfies 0 1 for any passive circuit, the maximum possible average power is 1000 W (when = 1 , for a purely resistive circuit). For circuits containing inductive or capacitive elements, Thus, the average power can be exactly 1000 W or less than 1000 W .

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