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Question
A meter gauge train is heading north with speed 54 km/hr in earth's magnetic field 3 x 10-4T. The e.m.f. induced across the axle joining the wheels is ..........
(a) 0.45 mV
(b) 4.5 mV
(c) 45 mV
(d) 450 m V
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Solution
(b) 4.5 mV
e = vlb
`= 54 xx 5/18 xx 1 xx 3 xx 10^(-4)`
`= 45 xx 10^(-4) = 4.5 mV`
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