A thin ring of radius 10 cm carrying a current of 10 A is placed in a uniform magnetic field of induction 1.5 T with its plane perpendicular to the field. Then tensile or compressive force induced in the wire of the ring is 

Case (i): For clockwise current and magnetic field into the paper, force induced in the wire is tensile in nature.

 Force acting on each element of length $∆\mathrm{L}$ of the ring is radially outwards and $\mathrm{F}=\mathrm{i}.∆\mathrm{L}.\mathrm{B}$

F' = Force per unit length $=\frac{\mathrm{F}}{∆\mathrm{L}}=\mathrm{iB}$

For equilibrium, $2\mathrm{T}=\mathrm{F}\text{'} \mathrm{x} 2\mathrm{r}=\mathrm{iB} \mathrm{x} 2\mathrm{r}$

$\therefore \mathrm{T}=\mathrm{irB}=10 \mathrm{x} 0.1 \mathrm{x} 1.5 \mathrm{N}=1.5 \mathrm{N}$

Case (ii): For clockwise current and magnetic field out of the paper, force induced in the wire is same as in the above case except that now it is compressive in nature.