Question

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

Answer 1

Given

Length of coil is $l=2.2 m$

Magnetic field at the center of the solenoid is $B=0.4 T$

The energy stored in the solenoid is

$U=\frac{B^2Al}{2\mu_0}=\frac{(0.4)^2(\pi(0.45)^2)(2.2)}{2(4\pi\times10^{-7} )}$

$=8.91\times10^4 T$