PHYSICS · Multi-part · A Level · Physics · Fields and their consequences · Fields and their consequences
Problem
A rectangular coil of 200 turns, each turn measuring 20cm×10cm, is mounted so that it can rotate uniformly about an axis perpendicular to a uniform magnetic field of flux density 0.50T. The coil is driven at 1500revmin−1 and is connected across an external resistor of 10Ω.
(i) Derive an expression for the maximum value of the alternating emf induced in such a coil when it rotates with constant angular speed in a uniform magnetic field.
(ii) Using the data given, calculate the maximum emf induced and the instantaneous emf after t=3001s from the moment the coil’s plane is perpendicular to the magnetic field.
(iii) Determine the rms value of the induced emf, the rms current through the external resistor, and the average power dissipated in the resistor.