Two parallel rails of a railways track insulated from each other and with the ground are connected to a millivoltmeter. The distance between the rails is one metre. A train is travelling with a velocity of 72 km− h−1 along the track. The reading of the millivotmeter (in mV ) is : (Vertical component of the earth's magnetic induction is 2×10−⁵ T )
a. 1.44
b. 0.72
c. 0.4
d. 0.2