TS EAMCET · Physics · Magnetic Effects of Current
A bar magnet has coercivity \(4 \times 10^3 \mathrm{Am}^{-1}\). It is placed inside a solenoid of \(12 \mathrm{~cm}\) length and 60 turns. The current that should be passed through the solenoid to demagnetise the bar magnet is
- A \(2A\)
- B \(4A\)
- C \(6A\)
- D \(8A\)
Answer & Solution
Correct Answer
(D) \(8A\)
Step-by-step Solution
Detailed explanation
Coercivity of bar magnet, \(\mathrm{H}=4 \times 10^3 \mathrm{~A} / \mathrm{m}\) Length of solenoid, \(\mathrm{L}=12 \mathrm{~cm}=0.12\) Number of turns, \(\mathrm{N}=60\) turns \(\mathrm{n}=\frac{\mathrm{N}}{\mathrm{L}}=\frac{60}{0.12}=500 \mathrm{turn} / \mathrm{m}\) Current,…
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