Question

The figure gives experimentally measured $B\text{vs}H$ variation in a ferromagnetic material. The retentivity, co-ercivity and saturation magnetization, respectively, of the material are:

• A. $\text{1.5 T, 50 A/m and 2.0 T}$
• B. $\text{1.5 T, 50 A/m and 1.0 T}$
• C. $\text{150 A/m, 1.0 T and 1.0 T}$
• D. $\text{1.0 T, 50 A/m and 1.5 T}$

Answer 1

The correct option is D $\text{1.0 T, 50 A/m and 1.5 T}$


Initially, The $B$ value increases with $H$ value, but becomes constant even when $H$ is increased. This constant value of $B$ is called saturation magnetization.

In the graph,
$\text{Saturation Magnetization}=1.5\text{T}$

Retentivity: The magnetization retained$\left(B\right)$ after the external field is removed $\left(H\right)$ is called retentivity.

$B$ value at $H=0$

From the graph, $\text{Retentivity}=1\text{T}$

Co-ercivity: The reverse external field required to demagnetize the material.

$H$ value for which $B$ becomes zero.

From the graph, $\text{Coercivity}=50{\text{Am}}^{-1}$

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