A coil having n turns and resistance R ohm is connected with a galvanometer of resistance 4R ohm. This combination is moved in a region where magnetic flux changes from W1 weber to W2 weber in t second. The induced current in the circuit is
−n(W2−W1)5 Rt
The rate of change in flux in a single loop is W2−W1t.
Hence, the voltage generated across all the loops is −n(W2−W1)t
The resistance of the coil is R+4R=5R
Therefore, the current is equal to −n(W2−W1)5Rt