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JEE Main 2019 (9 Jan, Shift 1) · Hysteresis, Soft Iron vs Steel & Shielding

Hysteresis, Soft Iron vs Steel & Shielding question from JEE Main 2019 (9 Jan, Shift 1)

Q14JEE Main 2019 · 9 JAN · SHIFT 1Easy

Hysteresis, Soft Iron vs Steel & Shielding

A bar magnet is demagnetized by inserting it inside a solenoid of length 0.2 m, 100 turns, and carrying a current of 5.2 A. The coercivity of the bar magnet is:

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Answer: (b)

  1. To demagnetise the magnet, the solenoid field must equal the coercivity: H=nI=NLIH = nI = \dfrac{N}{L} I.
  2. H=1000.2×5.2=500×5.2H = \dfrac{100}{0.2} \times 5.2 = 500 \times 5.2
  3. H=2600 A/mH = 2600\text{ A/m}
  4. So the answer is (b) 2600 A/m.
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