Question

A bar magnet has coercivity `4xx10^(3) Am^(-1)`. It is desired to demagnetise it by inserting it inside a solenoid `12 cm` long and having `60` turns. The current that should be sent through the solenoid is
A. 8 Å
B. 6 Å
C. 4.5 Å
D. 2 Å

Answer 1

H = ni
`i= (4 xx 10^(3) xx 12 xx 10^(-2))/(60) = (12)/(15) xx 10 = (120)/(15) = (40)/(5) = 8 A`