Question

- A Bulb is Connected in Series with a Variable Capacitor and an Ac Source as Shown. What Happens to the Brightness of the Bulb When the Key is Plugged in and Capacitance of the Capacitor is Gradually Reduced? - Capacitors and Capacitance

Answer 1

Brightness decreases, as Xc=1/wC
And C is decreasing Xc, capacitive reactance increases, current to the bulb Dec, hence bulb glows dimly.

Answer 2

Capacitors and Capacitance

Explanation:

When the capacitance of the capacitor is gradually reduced, the capacitive reactance will increase proportionately.

We know that Xc = 1 / (2 × π × f × C) where Xc is reactance, f is frequency and C is capacitor.

So overall resistance of the circuit will also increase, which will cause the amount of current flowing through the circuit to decrease. This will result in the brightness of the bulb being reduced.