An electric lamp having coil of negligible inductance connected in series with a capacitor and an a.c. source is glowing with certain brightness, Fig. How does the brightness of the lamp change on reducing (i) capacitance (ii) frequency

Explanation

When AC source is connected , the capacitor offers capacitative reactance ` X_C-underset(omegaC)(1)=underset(2pinuC)(1)`. The current flows in the circuit and the lamp glows.
(i) On reducing capacitance, `C,X_C` increases. Therefore, the brightness of the bulb reduces.
(ii) On reducing frequency `v,X_C` increases. Therefore, the brightness of the bulb reduces.