The magnetic flux across a loop of resistance `10Omega` is given by `phi=(5t^(2)-4t^(2)+1)Wb`. How much current is induced in the loop after `0.2` s?

Options

A. 0.4 A
B. 0.2 A
C. 0.04 A
D. 0.02 A

Answer

B

Explanation

Magnetic flux, `phi=(5t^(2)-4t+1)Wb`
`therefore" "(dphi)/(dt)=10t-4"Wbs"^(-1)`
The induced emf, `e=(-dphi)/(dt)=-(10t-4)`
At, t = 0.2 s, `e=-(10xx0.2-4)=2V`
The induced current, `I=(e)/(R)=(2V)/(10Omega)=0.2A`