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. $520$ A/m
• B. $2600$ A/m
• C. $285$ A/m
• D. $1200$ A/m

Answer 1

The correct option is B $2600$ A/m

Coercivity $=H=\frac{B}{{\mu }_0}$
$=ni=\frac{N}{l}i=\frac{100}{0.2}\times 5.2=2600$ A/m