You must have heard about the high speed ‘maglev’ trains that operate at an incredible speed range of 400 – 600 km/hr. Maglev stands for ‘magnetic levitation’. The word ‘levitation’ is defined as a process by which an object is suspended against gravity without any physical contact.
Every magnet has a north pole and a south pole; like poles repel and unlike poles attract each other. Permanent magnets are always magnetic. Let us think of three bar magnets lined up on the floor. The magnet in the front is pulling with an attracting magnetic pole and the magnet in the back is pushing with a repulsive force. What happens now is that the magnet in the middle moves forward. This is the basic principle of how a maglev train moves forward.
The tracks are referred to as guide ways. A maglev's guide way has a long line of electromagnets. Electromagnets are magnetic only when electric current flows through them. Also the north and the south poles are related to the direction of the current. If the direction is reversed, the poles are reversed. These magnets pull the train from the front and push it from behind. The electromagnets are powered by controlled alternating currents, so they can quickly change their pull and push poles, and thus continually propel the train forward.
Guide ways have metal coils that are electrified. We know magnetic fields are generated when there is current flow. This field created by the electrified coils in the guide way walls and the track combine to propel the train avoiding the use of fossil fuels. Under the train’s body there are large magnets. The interaction between these magnets and the magnetic coils in the guide way causes the train to levitate. Thus magnetic levitation is used to suspend trains without touching tracks. The lack of friction enables these trains to reach very high speeds.