Battery, copper wire and magnets: the simplest electric train in the world

In this YouTube video you will not see anything special: battery coil of copper wire and some magnets. All together they make something that can be called "train". Looks interesting, but actually running the experiment?

 

If you pass a current through the coil (in the video this is a copper spiral), the magnetic field is formed:





Magnetic field is concentrated almost uniformly at the center of a long solenoid; the field outside is weak and diffuse

If the field lines are exactly parallel, the bar magnet strength has no effect. But at the ends of the coil where the lines of force diverge, the bar magnet will be pulled into the coil, or pushed out of it, depending on where you shove it.

The trick of this video is that the magnets are made of a conductive material and connect terminals of the battery with copper wire, so the battery, magnets and copper wire form a circuit which generates a magnetic field in the vicinity of the battery. Geometry automatically puts the magnets on the ends of the generated magnetic field, so the magnets force is exerted.

Magnets carefully aligned so the force on both magnets points in the same direction, with the result that the magnets and battery move. But as the magnetic field moves with them and get constant movement.

If you turn the two magnets at both ends of the battery, the battery and the magnets will move in the opposite direction. If you turn only one magnet, the two magnets will pull and push in different directions, so the battery will not move.

Source: hi-news.ru