Question

A bar magnet is demagnetized by inserting it inside a solenoid of length $0.2\text{m}$, $100\text{turns}$, and carrying a current of $5.2\text{A}$. The coercivity of the bar magnet is:

• A. $285{\text{Am}}^{-1}$
• B. $1200{\text{Am}}^{-1}$
• C. $2600{\text{Am}}^{-1}$
• D. $520{\text{Am}}^{-1}$

Answer 1

The correct option is C $2600{\text{Am}}^{-1}$

$\text{Coercivity,}H=\frac{B}{{\mu }_0}$

$\text{Here},B={\mu }_{0}ni(\text{Where}n=\frac{N}{l})$

$\Rightarrow H=\frac{N}{l}i=\frac{100}{0.2}\times 5.2$

$\Rightarrow H=2600{\text{Am}}^{-1}$

Hence, option $\left(B\right)$ is correct.