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

Answer

A

Explanation

We know that `e = - (dphi)/(dt)`
` = -(d)/(dt) (6t^(2) - 5t+1)`
` e=- 12 t + 5`
` e= - 12 xx 0.25 + 5 = 2V`
`therefore " " I =(e )/(R) = (2)/(10) = 0.2A`
Reading of the ammeter.