Same chapter3 marksDifficulty: Medium
A circular coil of 100 turns and radius 0.1 m carries a current of 2 A. Find the magnetic field at its centre. Take μ0 = 4π × 10−7 T m A−1.
Magnetic Effects of Current and Magnetism
3 marksDifficulty: Medium
Distinguish between diamagnetic, paramagnetic and ferromagnetic substances, with one example of each.
Original Khojo Papers practice question — not from a past board paper.
Answer
Diamagnetic substances are feebly repelled by a magnet and have a small negative susceptibility, as bismuth has. Paramagnetic substances are feebly attracted and have a small positive susceptibility, as aluminium has. Ferromagnetic substances are strongly attracted, have a very large positive susceptibility and retain magnetism, as iron does.
No citable source has been recorded for this record. Treat it as practice material, not as fact.
Explanation
A ferromagnetic material becomes paramagnetic above its Curie temperature.
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