JEE Previous Year Question

The current required to be passed through a solenoid of 15 cm length and 60 turns in order to demagnetise a bar magnet of magnetic intensity 2.4 x 103 is A

Topic: JEE PYQ

Answer: 6. Full step-by-step solution below.

Correct answer: 6

Solution

(6)
The magnetic intensity is

For M = 0, it can be written

The data given is
H = 2.4 x 103 A
= 15 x 10-2 m
N = 60
Using the relation, and H = ni, the value of the current is,

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