Question

A mini generator has a coil of 1000 turns, each of area 10^-2m² . The coil is placed with its plane perpendicular to a uniform magnetic field of intensity 25 mT and is rotated at a uniform rate of 100 rotations per second. The magnitudes of the average of the emf generated, during the four quarters of its rotation, equal, respectively

(1) 0 volt, 0 volt, 0 volt, 0 volt

(2) 0 volt, 100 volt, 0 volt, 100 volt

(3) 100 volt, 0 volt, 100 volt, 0 volt

(4) 100 volt, 100 volt, 100 volt, 100 volt

Answer 1

(4) 100 volt, 100 volt, 100 volt, 100 volt

The flux, linked with the coil, at any instant is

ϕ = NAB cos ωt

∴ Instantaneous induced emf, ε , is given by

The average, of this, over success four quarters of the cycle, are given by 4/T times the integral of the above, from