Physics - Magnetism Question with Solution | TestHub

A current of I is flowing in a wire which is in the centre of an infinitely long straight metal tube. The radius of the tube is r, the width of its wall is $\mathrm{d}(\mathrm{d}\ll \mathrm{r})$, and the young modulus of its material is E. The amount by which the radius of the tube changes if a current of magnitude I is flowing in the tube which is opposite to the current in the wire is $\frac{{\mu }_0{\mathrm{I}}^2}{\alpha {\pi }^2\mathrm{dE}}$. The value of $\alpha$ is:-