Fast and safe modes of transportation are very important in connecting people to their workplaces. Often, residents who live in less urban areas rely on forms of public transportation, such as trains and buses, to get to their jobs in the city. While the US has not prioritized the development of these unique trains, they are gaining popularity quickly in China, Japan, South Korea. China recently built the world’s fastest train for public use, which can travel at up to 373 miles per hour (mph). The secret lies in something that we often play with when we’re bored: magnets.
Maglev is short for “magnetic levitation,” the underlying mechanism that makes these trains seem to be gliding at high speeds. Magnetic metals, such as iron, nickel, and cobalt, have two poles: a north pole and a south pole (similar to the Earth itself). While opposite poles attract, two of the same poles repel one another.
Source: Encyclopedia Britannica
All maglev trains take these attractive and repulsive properties of magnets to make the train levitate as it moves. The magnetic poles on the bottom of the maglev train are the same as the magnetic poles of the rails below it, causing the train to levitate due to repulsion. In the meantime, magnets on the side of the train both attract and repel magnetic plates on the railway to propel the train forward.
Source: U.S. Department of Energy
To review: repulsion forces between the bottom of the train and the rail cause the train to levitate. Attraction and repulsion forces between the sides of the train and the platforms on the sides of the train make the train move forward.
The repulsion forces that make the train levitate are pretty straightforward (see diagram above). However, the forward movement of the train depends on two main concepts: electromagnetism and superconductivity. Electromagnetism is the powering of a magnet from an electrical current. For maglev trains to move forward, alternating magnetic poles on the platforms next to the train have to be turned on so that like poles can repel one another and opposite poles can attract one another (see image below). The faster that these poles are alternated by electricity, the faster the train will go. Meanwhile, something needs to make these magnets as strong as they are to levitate the train and push it forward–this ability comes from the superconductivity of the magnets. Superconductivity refers to the enhanced ability of metals to conduct a magnetic force when they are cooled to very low temperatures. Basically, for a maglev train to glide forward, its magnets must be cooled down to low temperatures to strengthen their force, and electricity must be used to switch the poles of the magnets next to the train as the train glides by.
Source: University of Technology Petronas
As you can imagine, there are some downsides to maglev trains, such as the energy cost of cooling down the metals underneath the train and the electricity cost of powering the magnets underneath and next to the train. While maglev trains are expensive, they do have quite some benefits over traditional trains. Since they do not make contact with the rails underneath, damage to the train’s underside is less likely. In addition, they are faster and quieter than traditional trains. As more maglev trains are built and glide along their tracks, it’s important for us to know about how they work!
