Question

The magnetic flux through a coil perpendicular to its plane is varying according to the relation $\varphi = 5t^3 + 4t^2 + 2t - 5$ Weber. If the resistance of the coil is 5 ohm, then the induced current through the coil at t = 2 s will be,

• A. 15.6 A
• B. 16.6 A
• C. 17.6 A
• D. 18.6 A

Answer 1

Answer: (A)

15.6 A

Answer 2

$\text{EMF} = -\frac{d\Phi}{dt} = -(15t^2 + 8t + 2)$

$i = \frac{\lvert \text{EMF} \rvert}{R} = \frac{15t^2 + 8t + 2}{5}$
at t = 2
$i(t=2) = \frac{15(2)^2 + 8(2) + 2}{5}$
$i=15.6A$
So,correct option is (A)