Question

Magnetic flux (in weber) in a closed circuit of resistance $20 \,\Omega$ varies with time $t ( s )$ as $\phi=8 t^2-9 t+5$. The magnitude of the induced current at $t =0.25\, s$ will be ______$mA$

Answer 1

The correct answer is 250
ϕ=8t2−9t+5
emf=−dtdϕ​=−(16t−9)
At t=0.25s
Emf=−[(16×0.25)−9]=5V
Current = Resistance Emf ​=20Ω5V​
=41​A=41000​mA=250mA