A coil having n turns and resistance R`Omega` is connected with a galvanometer of resistance 4 R`Omega` . 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 ____

Options

A. `(W_2-W_1)/(5Rnt)`
B. `-(n(W_2-W_1))/(5Rt)`
C. `-(W_2-W_1)/(Rnt)`
D. `-(n(W_2-W_1))/(Rt)`

Answer

B

Explanation

Induced current `I=-(N Deltaphi)/(R. Delta t) =-(N DeltaW)/(R. Deltat)` `[because phi=W]`
`therefore I=-(n(W_2-W_1))/((R+4R).t) [ because phi=W]`
`therefore I=-(n(W_2-W_1))/((R+4R).t)[ because N=n]`
`therefore I=-(n(W_2-W_1))/(5Rt) [ because Delta t=t]`