RL and RC Series Circuits
A light bulb and an inductor coil are connected to an ac source through a key as shown in the figure below. The key is closed and after sometime an iron rod is inserted into the interior of the inductor. The glow of the light bulb

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Answer: (b)
- Bulb and inductor are in series with the AC source.
- Inserting an iron rod increases , so increases.
- Impedance rises and current falls, so the glow decreases.
- So the answer is (b) decreases.