Q178 / 180 · KCET 2014 · Physics

The average power dissipated in A.C. circuit is \( 2 \) watt. If a current flowing through a circuit is \( 2 \)
\( A \) and impedance is \( 1 \Omega \), what is the power factor of the \( A C \) circuit?

  • Correct answer
    A
    \( 0.5 \)
  • B
    \( 11 \)
  • C
    \( 00 \)
  • D
    \( \frac{1}{\sqrt{2}} \)

Solution

Power of ac circuit is given as $P=V I \cos \phi$ Using Ohm's law, $V=I R$ $P=I^{2} Z \cos \phi$ Given, $P=2 W ; I=2 A ; Z=1 \Omega$ Substituting the values, we get $2 W=(2)^{2} \times 1 \times \cos \phi$ $\Rightarrow \cos \phi=\frac{2}{4}=\frac{1}{2}=0.5$ Therefore, power factor of ac circuit is $0.5$.

Hence, the correct answer is option: 'A'.

Relevant Questions