A light bulb connected in series with a capacitor and an a.c. source is glowing with a certain brightness.…
A light bulb connected in series with a capacitor and an a.c. source is glowing with a certain brightness. On reducing the capacity of capacitance and frequency of source, the brightness of the lamp (respectively)
is reduced, is increased
is reduced, is reduced
is increased, is reduced
is increased, is increased
Solution
The capacitive reactance is given by $\mathrm{X}_{\mathrm{C}}=\frac{1}{2 \pi \mathrm{fC}}$ If f or C is reduced, $\mathrm{X}_{\mathrm{C}}$ will also increase. This results in the increase of the total impedance of the circuit. Hence, both the current and brightness will decrease.