Question

The coercivity of a magnet is 5 × \(10^3\) A/m. The amount of current required to be passed in a solenoid of length 30 cm and the number of turns 150, so that the magnet gets demagnetised when inside the solenoid is …………A.

Answer 1

Correct answer is : 10 

\(\mathrm{H}_{\mathrm{c}}=\frac{\mu_{\mathrm{o}} \mathrm{ni}}{\mu_{\mathrm{o}}}\)

\(5 \times 10^{3}=\frac{150}{30} \times 100 \times \mathrm{i}\)

\(\frac{50}{5}=\mathrm{i}\)

\(\mathrm{I}=10\)