A coil of inductance L is connected in series with a bulb B and an AC supply. Brightness decreases when:
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Question

A coil of inductance L is connected in series with a bulb B and an AC supply. Brightness decreases when:

G1 Physics · Accepted Answer

Step 1: Current I = V/Z controls bulb brightness. Step 2: X(L) = ωL increases when a ferromagnetic core is inserted (increasing inductance). Step 3: The current decreases, causing the bulb to dim. Correct D. Final answer: (D) an iron rod is inserted in the coil.