A circular loop with a radius of 15 cm is placed in a homogeneous magnetic field with a density of 1 T. We attach the loop to an axis that is perpendicular to the lines of the magnetic field so that the lines of the magnetic field do not pierce its plane. At the same time, a torsion spring with a torsion constant of 0.4 N m is attached to the axle. Calculate the current through the loop if it (together with the spring) is rotated by 
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