A magnet has coercivity of 3×103 Am−1. It is kept in a 10cm long solenoid with a total of 50 turns. How much current has to be passed through the solenoid to demagnetize it?
μ∘H=μ∘nIGiven:
where H=3×10−3Am−1=coercivity
n=number of turns per unit length =500.1=500m−1
To find: I= current
Now
H=nI
I=6×10−6A=6μA