Question

A resistor and an inductor are connected to an ac supply of $120\, V$ and $50\, Hz$. The current in the circuit is $3\, A$. If the power consumed in the circuit is $108 \, W$, then the resistance in the circuit is

• A. $12 \, \Omega$
• B. $40\, \Omega$
• C. $\sqrt{(52 \times 28)} \, \Omega$
• D. $360\, \Omega$

Answer 1

Answer: (A)

In an ac circuit, a pure inductor does not consume any power. Therefore, power is consumed by the resistor only.
$\therefore P=I_{ v }^{2} R $
or $ 108=(3)^{2} R $ or $ R=12 \, \Omega$