Question

The magnetic flux $\phi$ (in weber) linked with a coil of resistance 10 $\Omega$ varies with time t (in second) as $\phi$ = $8t^2 - 4t + 1$. The current induced in the coil at t = 0.1 sec is

• A. 10 A
• B. 0.24 A
• C. 1 A
• D. 0.38 A

Answer 1

The Correct Option is B

E.m.f induced, $\varepsilon = \frac{-d \phi}{dt} = \frac{-d}{dt} ( 8t^2 - 4t + 1) = - [ (2 \times 8) t - 4] = - [16 t - 4 ] $ Here, $t = 0.1 s $ $\therefore$ $\varepsilon $ = - [16 $\times$ 0.1 - 4] = 4 - 1.6 = 2.4 V Current induced I = $\frac{\varepsilon}{R} = \frac{2.4}{10} $ = 0.24 A