A square coil of turns and side lies in a horizontal plane

PHYSICS · Multi-part · Fermi University Physics · Electricity, Magnetism & Electromagnetism · Electromagnetic induction and alternating-current circuits · Electromagnetic induction and alternating-current circuits

Electricity, Magnetism and Electromagnetism, Ch Faraday's law, motional emf and Lenz's law

Problem

A square coil of N=40N = 40 turns and side l=0.15 ml = 0.15\,\mathrm{m} lies in a horizontal plane, entirely inside a region where a uniform vertical magnetic field of magnitude B=0.30 TB = 0.30\,\mathrm{T} acts. The field is zero outside that region, and the boundary of the region is a straight vertical plane. The coil is pulled horizontally out of the field region at a constant speed v=0.25 m s−1v = 0.25\,\mathrm{m\,s^{-1}}, with two of its sides parallel to the boundary. The total resistance of the coil is R=5.0 ΩR = 5.0\,\Omega, and friction is ignored. ((a)) Find the magnitude of the emf while the coil is leaving the region. ((b)) For how long does this emf last? ((c)) Find the current in the coil. ((d)) Find the force needed to keep the speed constant.

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