Question

An $AC$ voltage 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 increased:

• A. (A)the bulb glows dimmer
• B. the bulb glows brighter
• C. total impedance of the circuit is unchanged
• D. total impedance of the circuit increases

Answer 1

The correct option is B the bulb glows brighter

$z=\sqrt{R^2+X_C^2}{X}_C=\frac{\omega }{c}$

if $\omega$ increases $X_C$ increases.

if $X_C$ increases $z$ increases.

We know that,$I=\frac{V_o}{\sqrt{R^2+X_C^2}}$

if $z$ increases then $I$ decreases.

If $I$ decreases then

The bulb glows dimmer.