Question

A coil of resistance $400\Omega$ is placed in a magnetic field. If the magnetic flux $\varphi \left(Wb\right)$ linked with the coil varies with time t (sec) as $\Phi =50t^2+4$
The current in the coil at t = 2 sec is

• A. 2A
• B. 1A
• C. 0.5A
• D. 0.1A

Answer 1

The correct option is C 0.5A

The magnitude of induced emf is

$|\epsilon |=|-\frac{d\varphi }{dt}|=100t$

By Ohm's law, current at $t=2$ is

$I=\frac{\epsilon }{R}=100t/400=100\left(2\right)/400=0.5A$