A coil having n turns and resistance `R Omega` is connected with a galvanometer of resistance `4R 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_(1)-W_(2)))/(Rnt)`
B. `-(n(W_(2)-W_(1)))/(5Rt)`
C. `-((W_(2)-W_(1)))/(5Rnt)`
D. `-(n(W_(2)-W_(1)))/(Rt)`

Answer

B

Explanation

`(d phi)/(dt)=((W_(2)-W_(1)))/(t)R_("tot")=(R+4R)Omega = 5R Omega`
`i=(nd psi)/(R_("tot")dt)=(-n(W_(2)-W_(1)))/(5Rt)" " (because W_(2) & W_(1) " are magnetic flux")`