A capacitor is connected in series with a lit bulb on an a.c. supply. What happens to the bulb’s brightness if a glass plate is inserted between the capacitor plates?
Correct answer A. It increases
Explanation
Glass acts as a dielectric and increases the capacitance. Capacitive reactance X = 1/(2πfC) therefore falls, more current flows, and the bulb glows more brightly.
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