A coil with a diameter of 20 cm can rotate about a vertical axis that coincides with one of the diameters of the coil.

A coil with a diameter of 20 cm can rotate about a vertical axis that coincides with one of the diameters of the coil. The coil was installed in the plane of the magnetic meridian and a current of 10 A was sent through it. What torque should be applied to the coil in order to keep it in its initial position?

To solve the problem, we will use the following formula:
d * A = I * d * F;
M * d * F = I * d * (B * n * R ^ 2 * sin a);
M = I * B * n * R ^ 2 * (d * (sin a) / d * Ф);
M = I * B * n * R2 ^ * cos a;
Then in the initial position, the angle Ф, will be equal to 0:
M = I * B * n * (d ^ 2/4);
M = 6.283 * 10 ^ -6 Nm.
Answer: M = 6.283 * 10 ^ -6 Nm.