Question

The magnetic flux linked with a coil, in webers, is given by the equation ɸ = 4t² – t + 7. Then the magnitude of induced emf at 2 sec will be ... 

(a) 15v

(b) 19v

(c) 17v 

(d) 21v

Answer 1

The correct option (a) 15 v  

Explanation:

ɸ = 4t² – t + 7

(dɸ/dt) = 8t – 1

e = – (dɸ/dt)

hence induced emf at t = 2 sec

e = |– (dɸ/dt)|

e = 8t – 1|_{at t = 2 sec}

e = (8 × 2) – 1 = 15 v