Question

Two parallel rails of a railway 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 traveling with a velocity of $72km/h$ along the track. The reading of the millivoltmeter (in $mV$ ) is :

(Vertical component of the earths magnetic induction is $2\times {10}^{-5}T$ )

• A. $144$
• B. $0.72$
• C. $0.4$
• D. $0.2$

Answer 1

Answer: (C)

$0.4$

$Emf=Bvl$
$=2\times {10}^{-5}\times 72\times \frac{1000}{3600}\times 1$
$=4\times {10}^{-4}V$
$=0.4mV$