A coil of resistance `400Omega` is placed in a magnetic field. If the magnetic flux `phi` (wb) linked with the coil varies with time `t` (sec) as `f=50t^(2)+4`, the current in the coil at `t=2` sec is

Options

A. `1A`
B. `0.5A`
C. `0.1A`
D. `2A`

Answer

B

Explanation

Induced emf of coil `E=|-(dphi)/(dt)|_(t)`
Given, `phi=510t^(2)+4and R=400Omega`
`E=|-(dphi)/(dt)|_(t=2)=|100t|_(t=2)=200V`
current in the coil `i=(E)/(R )=(200)/(400)=(1)/(2)=0.5A`