Question

The two rails of a railway track, insulated from each other and the ground, are connected to millivoltmeter. What is the reading of the millivoltmeter when a train passes at a speed of 180 km/hr along the track, given that the vertical component of earth's magnetic field is $0.2\times {10}^{-4}wb/m^2$ and rails are separated by 1 metre

• A. ${10}^{-1}volt$
• B. $10mV$
• C. $1volt$
• D. $1mV$

Answer 1

The correct option is D $1mV$

$\epsilon =Blv$
$=(0.2\times {10}^{-4})\left(1\right)(180\times 5/18)$
$={10}^{-3}V$
$=1mV$