Question

An a.c. generator consists of a coil of 50 turns and area `2.5 m^(2)` rotating att an angular speed of `60 rad s^(-1)` in a uniform magnetic field B = 0.3 T between two fixed pole pieces. The resistance of the circuit including that of coil is `500 Omega`. Find (i) the max. current drawn from the generator.
(ii) What will be the orientaiton of the coil w.r.t. the magnetic field to have (a) maximum (b) zero magnetic flux ?
(iii) Would the generator work if the coil were stationary and instead, the pole pieces rotated together with the same speed as above ?

Answer 1

(i) Here, `N = 50, A = 2.5 m^(2), omega = 60 rad s^(-1)`
`B = 0.3 T, R = 500 Omega, I_(0) = ?`
`I_(0) = (e_(0))/(R ) = (NAB omega)/(R ) = (50 xx 2.5 xx 0.3 xx 60)/(500)`
`= 4.5 A`
(ii) Magnetic flux will be max. if the coil is in the vertical position . On the other hand, magnetic flux will be zero if the coil is in the horizontal position.
(iii) Yes, the generator will work if the coil is stationary and instead, the pole pieces are rotated together.