Find the energy of the magnetic field of the solenoid, in which, with a current of 20A, the inductance is 0.5 G.

Given:
I = 20 A;
L = 0.5 G.
Find: W.
Decision:
Let’s write down the formula for finding the energy. W = LI ^ 2/2.
We know all the variables from this formula, which means that to find the answer, you just need to substitute them in the formula. Then we get W = 20 * 0.5 ^ 2/2 = 20 * 0.25 / 2 = 5/2 = 2.5 J.
Answer: 2.5