A solenoid with an iron core and a bulb are connected to a d.c. source. How does the brightness of the bulb change, when the iron core is removed from the solenoid?

When the iron core is removed, the solenoid’s inductance decreases, reducing opposition to current changes. However, in a d.c. circuit, inductance has minimal effect in steady state. The current remains the same, so the brightness of the bulb does not change.

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