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Single Phase Closed-Circuit

A closed-circuit, 500-turn coil, of resistance 100, and negligible inductance, is wound on a square frame of 40 cm side. The frame is pivoted at the mid points of two opposite sides and is rotated at 250 r/min in a uniform magnetic field of 60 mT. The field direction is at right angles to the axis of rotation.

For the instant that the e.m.f. is maximum :

(a) Draw a diagram of the coil, and indicate the direction of rotation, and of the current flow, the magnetic flux, the e.m.f. and the force exerted by the magnetic field on the conductors

(b) Calculate the e.m.f., the current and the torque, and hence verify that the mechanical power supply balanced the electric power produced.

Solution Preview

Please see the attached or full solution.

a) Let the coil is rotating about the z-axis ant at t=0 its plane is in x-z plane and parallel to magnetic field B which is along +x direction. The magnetic flux through the coil at that instant is zero but the rate of change of the flux through the coil is maximum and hence the induced EMF in the coil at this instant is maximum.
If the coil is rotating counterclockwise as seen ...

Solution Summary

The solution discusses the single phase closed-circuit.

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