Q. 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 increased
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
Explanation
(b) $Z = \sqrt{R^{2} + X_{C\ }^{2}}\ :I_{rms} = \frac{V_{rms}}{Z}:P = I_{rms}^{2}R$
Where $X_{C} = \frac{1}{\omega C}$
As $\omega$ is increased, $X_{C}$will decrease or$\ Z\ $will decrease$.$ Hence $I_{rms}\ or\ P\ $will increase$.$ Therefore, bulb glows brighter.
Hence the correct option is (b).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.