A coil with a diameter of 20 cm can rotate about a vertical axis coinciding with one of the diameters of the coil. The coil was installed in the plane of the magnetic meridian and a current I = 10 A was passed through it. Find the mechanical torque that must be applied to the coil in order to hold it in the initial position. The horizontal component of the earth's magnetic field induction is taken to be 20 µT.

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