Q.

A series R-C circuit is connected to an alternating voltage source. Consider two situations:

(p) When capacitor is air filled.

(q) When capacitor is mica filled.

Current through resistor is i and voltage across capacitor is V then                 [2015]

1 ip>iq  
2 Vp=Vq  
3 Vp<Vq  
4 Vp>Vq  

Ans.

(4)

Current through resistor,

i = Current in the circuit

    =V0R2+XC2=V0R2+(1ωC)2

Voltage across capacitor, V=iXC

      =V0R2+(1ωC)2×1ωC=V0R2ω2C2+1

As  Cp<Cq      ip<iq and Vp>Vq