Q. The two rails of a railway track insulated from each other and the ground are connected to a milli-voltmeter. What is the reading of the mV, when a train travels at a speed of 180 $kmh^{- 1}$ along the track, given that the horizontal components of earth’s magnetic field is $0.2 \times 10^{- 4}\ Wbm^{- 2}$ and the rails are separated by 1 m
A) $10^{- 2}\ $mV
B) 10 mV
C) 100 mV
D) 1 m V
Explanation
(d) $v = 180\ kmh^{- 1} = \frac{180 \times 1000}{60 \times 60} = 50\ ms^{- 1}$
$l\ \ = 1m,\ B = 0.2\ \times 10^{- 4}\ Wbm^{- 2}$
$e = Blv = 002 \times 10^{- 4} \times 1 \times 50 = 10^{- 3}$V=1mV
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.