The magnetic flux linked with coil, in weber is given by the equation, ϕ=5t2+3t+16. The induced emf in the coil in the fourth second is
10 V
30 V
45 V
90 V
|e|=dϕdt=ddt5t2+3t+16=(10t+3)
when t=3sec,e3=(10×3+3)=33Vwhen t=4sec,e4=(10×4+3)=43VHence emf induced in fourth second =e4−e3=43−33=10V