### A train travels using electromagnetic fields.

Watch The Video:

Other Demos of Interest:

 Electrochemical Circuit How a Rail Gun Works Simple Magneto-Motor

Teachable Topics:

• solenoid
• magnetic field
• electromagnetism
• circuit

Theory:

The magnets and the copper wire are both conducting materials, so a circuit is completed around the battery, enabling the flow of current through the solenoid.

A current passing through the coils of the solenoid generates a magnetic field which is directed along the axis of the solenoid.

A magnet inside the solenoid will feel no force, as all of the magnetic field lines are in the same direction. However, a magnet placed at either end of the solenoid will feel a force because the magnetic field lines are non-uniform (they diverge).

In the case of our train, the only part of the solenoid that has current running through it is the region around the battery. Thus, the magnetic field is only generated through the segment of solenoid directly surrounding the battery, as that is the only region where current is flowing. At either end of our circuit then, the magnetic field lines diverge.

The magnets feel a force from these diverging field lines and since both the magnets are aligned in the same direction, this force causes them to move, propelling the train forward. As the train moves, the magnetic field travels with it, which keeps the train in motion.

Apparatus:

• AA battery
• Two spherical magnets
• uninsulated copper wire

Procedure:

• coil the copper wire loosely to make a "track"
• place magnets on either end of the battery, with both magnets aligned in the same direction to make a "train"
• place the "train" in the "track"