Have you ever wondered which type of electrical current is used to power electrified trains? If AC or DC is preferred, why is that the case?

Alternating current, aka AC, is an electrical current (flow of electrons) that reverses its direction many times a second at regular intervals. It is typically used in power supplies in many nations around the world.

The standard current used in places like the U.S. flips 60 times a second and is said to have a frequency of 60 Hz. In Europe and most other parts of the world, AC current typically has a frequency of 50 Hz or flips 50 times a second.