An `AC` voltage source of variable angular frequency `omega` and fixed amplitude `V_(0)` is connected in series with a capacitance `C` and an electric bulb of resistance `R` (inductance Zero). When `omega` is increase.

Options

A. The bulb glows dimme
B. The bulb glows brighter
C. Net impedance of the circuit remains unchanged
D. Total impedance of the circuit increases

Answer

B

Explanation

Given

`V=V_(0) sin omega t`
Reactance, `X_(C)=(1)/(omegaC)`
Net resistance, `R_("net")= sqrt(R^(2)+X_(C)^(2))`
`= sqrt(R^(2)+(1)/(omega^(2)C^(2))))`
Since `I=(V)/(R_("net"))`
`=(V)/(sqrt(V^(2)+(1)/(omega^(2)C^(2))))`
Hence `I prop omega` which means increase of `omega` will increase 1 and hence bulb glows brighter.