A coil having N turns and area A rotates in a uniform magnetic field B with angular velocity ω,

Then the peak value of the emf (V_{max}) induced in the coil is given by (V_{max}) = NABω

Now the fact is that the **area of the coil in the 2nd case is 4A** since the radius is doubled.

But the **number of turns will be N/2** in the second case since the length of the wire required for a turn is doubled.

If V_{1} and V_{2} are the peak values of the emf in the two cases,

We have V_{1}/V_{2} = 100 /V_{2} = NABω / [(N/2)×(4A)Bω]

Or, 100 /V_{2} = ½

from which

**V**_{2} = 200 volt.