Question

The correct plot of the magnitude of magnetic field $\vec{B}$ $vs$ distance $r$ from centre of the wire is, if the radius of wire is $R$

• A.
• B.
• C.
• D.

Answer 1

Answer: (B)

The magnetic field from the centre of wire of radius $R$ is given by
$B=\left(\frac{{\mu }_{0}I}{2R^2}\right)r\left(r<R\right)$
$\Rightarrow B\propto r$
and $B=\frac{{\mu }_{0}I}{2\pi r}\left(r>R\right)$
$\Rightarrow B\propto \frac{1}{r}$
From this descriptions, we can say that the graph $\left(b\right)$ is acorrect representation