A bulb and a capacitor are connected in series across an ac supply. A dielectric is then placed between the plates of the capacitor. The glow of the bulb:
To address this issue, it is necessary to comprehend the impact of a series-connected capacitor on a circuit containing a bulb and the consequences of introducing a dielectric into the capacitor.
Theoretical Background:
A capacitor introduces capacitive reactance into an AC circuit.
The capacitive reactance \(X_C\) is calculated using the formula: \(X_C = \frac{1}{2\pi fC}\), where \(f\) represents the AC supply frequency, and \(C\) is the capacitance.
The introduction of a dielectric between a capacitor's plates elevates its capacitance \((C = \kappa C_0)\), where \(\kappa\) is the dielectric constant, a value exceeding 1.
Effect of Dielectric on the Circuit:
With augmented capacitance \((C)\), the capacitive reactance \((X_C)\) diminishes.
Reduced reactance translates to lower circuit impedance, facilitating a greater current flow through the bulb.
Conclusion:
Consequently, the bulb's luminosity intensifies because the reduced impedance, a direct result of the increased capacitance from dielectric insertion, permits a higher current to pass through it.
Justification of Options:
Increases: Valid. This is due to decreased reactance and increased current.
Remains same: Invalid. Capacitance variations influence current flow.
Becomes zero: Invalid. Enhanced capacitance augments current, it does not cease it.
