The magnetic flux `phi` (in weber ) in a closed circuit of resistance 10`Omega` varies with time t (in secnod) according to equation `phi=6t^(2)-5t+1`. The magnitude of induced current at `t=0.25` s is

Options

A. 0.2 A
B. 0.6 A
C. 1.2 A
D. 0.8 A

Answer

A

Explanation

Induced emf
`e= -(d phi)/(dt)`
`=-(d)/(dt)(6t^(2)-5t+1)`
`=-12t+5`
At `t=0.25 s,`
`epsilon = -12 (0.25)+5 =2`volt
Induced current, `I=(epsilon)/(R )=(2)/(10)=0.2A`