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The potential differences across the resistance, capacitance and inductance are 80 V, 40 V and 100 V respectively in an L-C-R circuit. The power factor of this circuit is:
A
0.8
B
1.0
C
0.4
D
0.5
Explanation
$\cos\phi = V_R/\sqrt{V_R^2 + (V_L - V_C)^2}$.
Detailed Solution
$\tan\phi = \frac{V_L - V_C}{V_R} = \frac{100 - 40}{80} = \frac{3}{4} \Rightarrow \phi = 37^\circ$
Power factor $= \cos\phi = \cos37^\circ = \frac{4}{5} = 0.8$
Power factor $= \cos\phi = \cos37^\circ = \frac{4}{5} = 0.8$