Question

The relation between magnetic permeability, $\mu$ and field strength, $H$ for a specimen of iron is as follows $\mu =[\frac{0.4}{H}+12\times {10}^{-4}]\text{H/m}$ . The value of $H$ which produces flux density of $1\text{T}$ will be:

• A. $250\text{A/m}$
• B. $500\text{A/m}$
• C. $750\text{A/m}$
• D. ${10}^3\text{A/m}$

Answer 1

The correct option is B $500\text{A/m}$

Given:
$\mu =[\frac{0.4}{H}+12\times {10}^{-4}]\text{H/m}$
$B=1\text{T}$
We know that:-

$B=\mu H$

$\mu =[\frac{0.4}{H}+12\times {10}^{-4}]$

Multiplying both sides by H: -

$\mu H=[\frac{0.4}{H}+12\times {10}^{-4}]\times H$

$\Rightarrow B=0.4+12\times {10}^{-4}\text{H}$

$1=0.4+12\times {10}^{-4}H[\because B=1\text{T}]$

$\Rightarrow H=\frac{0.6}{12\times {10}^{-4}}$

$H=500\text{A/m}$