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Sequence Of Operation:
- The braking systems on many subway and rapid-transit cars made use of electromagnetic induction and eddy currents.
- An electromagnet attached to the train is positioned near to the steel rails.
- When a large current is passed through the electromagnet, a strong magnetic field is set up near the rails.
- The relative motion of the rails and the electromagnet will induce eddy currents in the rails.
- By Lenz’s law, these eddy currents will flow in a direction to oppose the changing flux.
- Hence, there will be a retarding force on the train.
- As the eddy currents decreases steadily in magnitude as the train slows down, the braking effect feels smooth to the passenger.
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