Question

A bar magnet is demagnetized by inserting it inside a length 0.2 m, 100 turns, and carrying a currents of 5.2 A. The coercivity of the bar magnet is :

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

Answer 1

The correct option is C 2600 A/m

Given: Length of the magnet= 0.2 m

Number of turns= 100

Current = 5.2 A

Solution: As we know, the coercivity of the bar magnet is given by,

$Coercivity=H=\frac{B}{{\mu }_0}=ni=\frac{N}{l}i$

where, B is the magnetic field and

${\mu }_0$ is the vacuum permeability

$=\frac{100}{0.2}\times 5.2$

$=2600A{m}^{-1}$

Hence, the correct option is (C).