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

Options

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

Answer

B

Explanation

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