JEE Main 2024 Physics question
The coercivity of a magnet is 5 × 10³ 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: 10
Solution
H = nI with n = 150/0.30 = 500 m⁻¹; I = 5000/500 = 10 A.