Question

An alternating supply of \(225\,\text{V}\) is applied across a circuit with resistance \(20\,\Omega\) and impedance \(45\,\Omega\). The power dissipated in the circuit is

• A. \(500\,\text{W}\)
• B. \(1000\,\text{W}\)
• C. \(550\,\text{W}\)
• D. \(2100\,\text{W}\) \bigskip

Hint:

For an AC circuit, \[ I=\frac{V}{Z} \] and the actual power consumed is \[ P=I^2R = VI\cos\phi. \] Only the resistive part of the circuit dissipates energy.

Answer 1

The Correct Option is A

Concept: AC circuit power: \(P = I^2R\). Find current from \(I = V/Z\).

Step 1: \(I = 225/45 = 5\) A. \(P = 5^2 \times 20 = 500\) W.

Step 2: Write the final answer. \(\boxed{P=500\,\text{W}}\)