A solenoid is 15 cm long,has a radius of 5 cm,and has 400 turns.If it carries a current of 4 A,the magnetic energy stored in the solenoid is

Question

Quizplus · Accepted Answer

The magnetic energy stored in a solenoid is given by the formula $ U = \frac{1}{2} L I^2 $, where $ L $ is the inductance of the solenoid and $ I $ is the current. The inductance $ L $ of a solenoid is given by $ L = \mu_0 \frac{N^2 A}{l} $, where $ \mu_0 $ is the permeability of free space ($4\pi \times 10^{-7} \, \text{T}\cdot\text{m/A}$), $ N $ is the number of turns, $ A $ is the cross-sectional area, and $ l $ is the length. Substituting the given values and calculating gives approximately 84.2 mJ.

A Solenoid Is 15 Cm Long,has a Radius of 5