Question

The magnetization curve for a ferromagnetic material is shown in the diagram. Select correct statements using the graph.

• A. The value of relative permeability is highest at point $\text{Q}.$
• B. The value of relative permeability is highest at point $\text{S}.$
• C. The value of relative permeability is lowest at point $\text{S}.$
• D. The value of relative permeability is lowest at point $\text{P}.$

Answer 1

Answer: (A), (C)

The value of relative permeability is lowest at point $\text{S}.$

We know that, $B={\mu }_o{\mu }_{r}H$

As, ${\mu }_o,{\mu }_r$ are constants, we can write

$B\propto H$, so that

$\frac{B}{H}={\mu }_o{\mu }_r=\text{constant}$

So, the slope of $B$ vs $H$ graph will be equal to ${\mu }_o{\mu }_r$.

The slope of the given graph is highest at point $\text{Q}$. Also, as ${\mu }_o$ is constant, the value of ${\mu }_r$ will be highest at point $Q$.

The slope of the given graph is lowest at point $\text{S}$. So, the value of ${\mu }_r$ will be lowest at point $S$.

Hence, options $\left(A\right)$ and $\left(C\right)$ will be the correct statements.

Why this Question? Tip: The slope of $B-H$ graph gives us the value of relative permeability.