Question

A coil having n turns and resistance R is connected with a galvanometer of resistance 4R. This combination is moved in time t seconds from a magnetic field $W_1$ weber to $W_2$ weber. The induced current in the circuit is

• A. $-\frac{W_2+W_1}{5Rnt}$
• B. $-\frac{n(W_2+W_1)}{5Rt}$
• C. $-\frac{(W_2+W_1)}{5Rnt}$
• D. $-\frac{n(W_2+W_1)}{Rt}$

Answer 1

The Correct Option is B

E = $n \frac{d \phi}{dt} \, \therefore \, I = \frac{\varepsilon}{R_{eq}} = \frac{nd \phi}{R_{eq} dt}$ $i.e.$ I = $- \frac{I}{R_{eq}} \frac{n(W_2 + W_1)}{t_2 - t_1} = - \frac{1}{(R + 4R)} \frac{n(W_2 + W_1)}{t}$ $i.e. $ I = $-n \frac{(W_2 + W_1)}{5 Rt}$