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

`e = (-d theta)/(dt) = (-d)/(dt) (6t^(2) - 5t+1)= - 12t + 5`
`e = - 12 (0.25) + 5 = 2 "volt"`
`i = (e)/(R) = (2)/(10) = 0.2A`