A bulb and a capacitor are connected in series to an a.c. source of variable frequency. How will the brightness of the bulb change on increasing the frequency of the a.c. source? Give reason.
Answer: The brightness increases.
Solution
The capacitive reactance is , so it falls as the frequency rises.
The impedance of the series combination therefore decreases, the current grows, and the bulb glows brighter.
The impedance of the series combination therefore decreases, the current grows, and the bulb glows brighter.
CBSE Class 12 Board · 2005 · All India · Subjective