Answer to Question #303781 in Electricity and Magnetism for Khateeja

Question

A solenoid of length 2.2m has a diameter of 0.9. The magnetic field at its centre is 0.4tesla . estimate the energy stored in the field of this coil.

Answer 1

Gives

$B=0.4T$

$l=2.2m$

$r=\frac{0.9}{2}$ m

$U=\frac{B^2}{2\mu}Al$

Area

$A=\pi r^2$

$$U=\frac{0.4^2}{2\times4\pi\times10^{-7}}\times\frac{\pi \times0.81\times2.2}{4}=89100J$$