Physics - Magnetism Question with Solution | TestHub

$n=40 \mathrm{t}\mathrm{u}\mathrm{r}\mathrm{n}\mathrm{s} \mathrm{c}{\mathrm{m}}^{-1}$

$=40\times 10^2 \mathrm{t}\mathrm{u}\mathrm{r}\mathrm{n}\mathrm{s} {\mathrm{m}}^{-1}$

$I=\mathrm{1.00 }\mathrm{A}$

The magnetic energy stored per unit volume in a solenoid

$U=\frac{B^2}{2{\mu }_0},B={\mu }_{0}nI$

(Magnetic field inside the solenoid)

$\therefore U=\frac{B^2}{2{\mu }_0}=\frac{{\left({\mu }_{0}nI\right)}^2}{2{\mu }_0}$

$=\frac{{\mu }_0^2{n}^2{I}^2}{2{\mu }_0}=\frac{{\mu }_0{n}^2{I}^2}{2}$

$=\frac{4\pi \times 10^{-7}\times {\left(40\times {10}^2\right)}^2\times {\left(1\right)}^2}{2}$

$=\mathrm{3.2 }\mathrm{\pi }\mathrm{J }{\mathrm{m}}^{-3}$