MHT CET 2024 Physics question

A coil of self inductance L is connected in series with a bulb B and a.c. source. Brightness of the bulb decreases when

(A)frequency of a.c. source is decreased
(B)number of turns in the coil is reduced
(C)a capacitance of reactance is included in the same circuit
(D)an iron rod is inserted in the coilCorrect

Answer: (D)

Solution

The bulb's brightness depends on the current , with . Brightness decreases only if increases. (A) Decreasing the frequency lowers , so the current rises and the bulb is brighter. (B) Fewer turns reduces (\propto$

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Question ID VK-093172