Question

A magnetising field intensity of $1000\frac{A}{m}$ produces magnetic flux density $0.25\frac{Wb}{m^2}$ in a ferromagnetic substance. The relative permeability of ferromagnetic substance is )(Approximately)

• A. $2.0\times {10}^4$
• B. $2.0\times {10}^2$
• C. $4.0\times {10}^3$
• D. $1.0\times {10}^5$

Answer 1

Answer: (B)

$2.0\times {10}^2$

Given: H=1000$\frac{A}{m}$ ,B=0.25$\frac{Wb}{m^2}$

Solution: By using the formula of relative permeability${\mu }_r=\frac{\mu }{{\mu }_0}$

$\mu =\frac{B}{H}$

$\mu =\frac{0.25}{1000}$

${\mu }_r=\frac{0.25}{1000\times 4\pi \times {10}^{-7}}$

${\mu }_r\approx 200$

Hence the correct option is B