Question

A millivoltmeter is connected in parallel to an axle of the train running with a speed of 180 km/hour. If the vertical component of earth's magnetic field is $0.2\times {10}^{-4}Wb/m^2$ and the distance between the rails is 1m, then the reading of voltmeter will be :

• A. 10${}^{-2}$ volt
• B. 10${}^{-4}$ volt
• C. 10${}^{-3}$ volt
• D. 1 volt

Answer 1

The correct option is C 10${}^{-3}$ volt

Reading of voltmeter= emf induced = $Blv=0.2\times {10}^{-4}\times 1\times 180\times \frac{1000}{3600}=1mV$