JEE Mains · Physics · STD 12 - 5. Magnetism and matter
The \(B-H\) curve for a ferromagnet is shown in the figure. The ferromagnet is placed inside a long solenoid with \(1000\, turns/cm\) . The current that should be passed in the solenoid to demagnetise the ferromagnet completely is
- A \(2\,mA\)
- B \(1\,mA\)
- C \(40\,\mu A\)
- D \(20\,\mu A\)
Answer & Solution
Correct Answer
(B) \(1\,mA\)
Step-by-step Solution
Detailed explanation
Given Number of turns, \(\mathrm{n}=1000\) \(turns/\)\(\mathrm{cm}=1000 \times 100\) \(turns\) \(/ \mathrm{m}\) Coercivity of ferromagnet. \(\mathrm{H}=100 \,\mathrm{A} / \mathrm{m}\) Current to demagnetise the ferromagnet, \(I=?\) Using, \(H=n I\) or,…
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