Magnetic Properties of Matter

JEE Main level, single correct, medium

51 of 57

Question 51 of 57

The B−HB-H curve for a ferromagnet is shown in the figure. The ferromagnet is placed inside a long solenoid with 1000turnscm−11000turns{cm}^{-1}. The current that should be passed in the solenoid to demagnetize the ferromagnet completely is,

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Answer: (C) 1mA1mA

The coercivity of ferromagnet, H=100Am−1H=100A{m}^{-1}, n×I=100n\times I=100
⇒I=100105=1mA\Rightarrow I=\dfrac{100}{{10}^{5}}=1mA.

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