Electromagnetic Induction and Alternating Current 2 Question 13
14. The two rails of a railway track, insulated from each other and the ground, are connected to a millivoltmeter. What is the reading of the millivoltmeter when a train travels at a speed of $180 km / h$ along the track given that the vertical components of earth’s magnetic field is $0.2 \times 10^{-4} Wb / m^{2}$ and the rails are separated by $1 m$ ? Track is South to North.
$(1981,4 M)$
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Answer:
Correct Answer: 14. $1 mV$
Solution:
- Potential difference between the two rails :
$V=B v l$ (When $\mathbf{B}, \mathbf{v}$ and $\mathbf{I}$ all are mutually perpendicular to each other)
$$ \begin{aligned} & =\left(0.2 \times 10^{-4}\right) \quad 180 \times \frac{5}{18} \\ & =10^{-3} V=1 mV \end{aligned} $$
