Q.

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   [2016]

1 0.4  
2 0.5  
3 0.8  
4 1.0  

Ans.

(3)

Here, VR=80 V, VC=40 V, VL=100 V

Power factor, cosϕ=RZ=VRV=VRVR2+(VL-VC)2

=80(80)2+(100-40)2=80100=0.8