Question

The impedance of a circuit consists of 3 ohm resistance and 4 ohm reactance. The power factor of the circuit is

• A. 1.0
• B. 0.8
• C. 0.6
• D. 0.4

Answer 1

The correct option is C 0.6

Calculation of power factor.
We know that power factor,
$cos\varphi =\frac{R}{Z}$

Given,
Resistance, R = $3\Omega$

Reactance, X = 4 $4\Omega$

Then,
Impedance,

$Z=\sqrt{R^2+X^2}=\sqrt{3^2+4^2}=5$
$\Rightarrow cos\varphi =\frac{3}{5}=0.6$

Hence, option (B) is correct.