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Make a magnetic rail gun

By , 1 August 2013

Electricity, magnets, momentum and cool slow-mo footage. It’s all in our video: take a look!

explosion hazard iconSafety: Ask an adult to supervise this activity. Wear safety glasses when using these rare earth magnets. If they collide together hard enough, chips of magnet can fly off them. Also be careful when handling the magnets, as they can pinch your skin. Keep magnets out of reach of small children and pets.

Video transcript available here.

Both the ring launcher and the rail gun use called Lenz’s Law to give an object momentum. Lenz’s Law can be observed when a magnet moves over a piece of wire.  A current is induced in the wire by the moving magnetic field.  Similarly, a current flowing along a wire creates a magnetic field.

In the rail gun, the ‘bullet’ is made from two cylindrical magnets on the ends of a metal rod.  A current flows down one rail and over the bullet.  This flowing current creates a magnetic field that repels the magnets, causing the bullet to move. Increasing the size of the rail gun’s battery will make the bullet move faster.

Teacher’s notes with curriculum links available here.


  1. Reblogged this on News @ CSIRO and commented:
    Our CSIROhelix peeps look at electricity, magnets & momentum with cool slow-mo footage.


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