Question

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
(A) 285 A/m (B) 2600 A/m
(C) 520 A/m (D) 1200 A/m
[JEE Main 2019]

Answer 1

Answer:

I think ans. is (C) 520 A/m

Answer 2

The coercivity of the bar magnet is 2600A/m

given-

length = 0.2 m

turns=100

i=5.2A

1.formula for magnetic field inside solenoid

2.B=μ₀nI( formula for calculating magnetic field).....1.

also B=μ₀H( also a formula for calculating magnetic field)......2.

comparing above equations we get H=nI

=N/L*I

3.now substitute all values for

=100/0.2*5.2

=100/2*52

=26*100

=2600A/m