JEE MainPhysicsModerateMagnetism

The coercivity of a small magnet where the ferromagnet gets
demagnetized is 3 × 10^3 Am^-1. The current required to be passed in
a solenoid of length 10 cm and number of turns 100, so that the magnet
gets demagnetized when inside the solenoid, is

Show answer and solution

For solenoid

\frac{B}{\mu_{0}} = H

B = \mu_{0}nI

H = nI

\Rightarrow 3 \times 10^{3} = \frac{100}{0.1} \times I

Ι = 3A

Source: Grass-G / P-13 Physics paper 4 Nov.docx

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