Two rails of a railway track insulated from each other and the ground are connected to a milli voltmeter. What is the reading of voltmeter, when a train travels with a speed of 180 km/hr along the track. Given that the vertical component of earth's magnetic field is  $0.2\times {10}^{-4}\text{ weber }/{\mathrm{m}}^2$ and the rails are separated by 1 metre

• A

  10^-2 volt

• B

  10^-4 volt

• C

  10^-3 volt

• D

  1 volt