A coil of resistance 100 `Omega` having 100 turns is placed in a magnetic field. A galvanometer of resistance `400 Omega` is connected in series with it. If the coil is brought from the present magnetic field to another magnetic field in `(1)/(10)s`, determine the average emf and the current. Given, the initial and final magnetic flux linked with each turn of the coil are 1 mWb and 0.2 mWb respectively.

Explanation

Change in magnetic flux for each turn
`=0.2-1=-0.8mWb`
So, change in magnetic flux for 100 turns
`=100xx(-0.8)mWb=-0.08Wb`
Hence, the magnetic of average emf induced = the negative of the rate of change of magnetic flux
`=-(-(0.08Wb)/((1)/(10)s))=0.8V`
The equivalent resistance of the circuit = 100 + 400 = 500 `Omega`.
Hence, the average induced current = `(0.8V)/(500Omega)=0.0016A=1.6mA`.