AP EAMCET Engineering 25 Apr 2017 Shift 1 Paper

A circular coil of radius 9 cm carrying a current of 2A is free to rotate about an axis in its plane perpendicular to an external magnetic field of π×10−2 T. When the coil is turned slightly and released, it oscillates about its stable equilibrium with a time period of

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s. If the moment of inertia of the coil about its axis of rotation is 9×10−5 kgm2, the number of turns of the coil is_____.