Задача 30045.

The current I = 0.6 A. The wires with a diameter D = 0.4 mm fit tightly to each other. Find the energy of the magnetic field in the steel core of the toroid, if the cross -sectional area is s = 4 cm^2, the diameter of the middle line d = 30 cm.

A detailed solution with a brief note of the conditions, formulas and laws used in the solution, the derivation of the calculation formula and the answer.
If you have any questions about the solution, write. I try to help.