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MODEL PAPER 2 — Physics STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 SciencePhysicsMODEL PAPER 21 Mark
Question
Assertion (A): A bulb connected in series with a solenoid is connected to ac source. If a soft iron core is introduced in the solenoid, the bulb will glow brighter.
Reason (R): On introducing soft iron core in the solenoid, the inductance increases.
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Answer

(d) A is false but R is true.
Explanation: A is true but R is false.
On introducing soft iron core, the bulb will glow dimmer. This is because on introducing soft iron core in the solenoid, its inductance L increases, the inductive reactance, $X _{ L }=\omega L$ increases and hence the current through the bulb decreases.

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