Te Reo Physics Resources

Multimedia Physics and Science Teaching Resources


Trick Magnet | Auto Nuka


One of two apparently identical steel rods passes easily between the poles of a magnet while the other unavoidably sticks to the magnet. One is stainless steel, the other mild steel.

Principles Illustrated
Magnetic and non-magnetic materials.



English version

Te Reo Māori Version


This demonstration is a lot of fun and takes only a short time to do. You’ll need similar looking mild steel and stainless steel bars and a strong magnet. We can bring this demonstration to you if you are in the Wellington area. As an alternative, we may be able to post the steel rods to you if you have a strong magnet such as the one featured in the video.

Mild steel
The Trick
Mild steel
The Trick

Other Information


People with pacemakers or other medical electronics should never approach strong magnets!
Individual teachers are responsible for safety in their own classes. Even familiar demonstrations should be practised and safety-checked by individual teachers before they are used in a classroom.

Strong magnet warning
Strong magnet warning

Notes, Applications, and Further Reading

Eddy current drag is used to make brakes in certain applications. See for example the following exchange on physlink: eddy currents brakes . Also see a discussion of eddy currents in Wikipedia.


This teaching resource was developed by the Te Reo Māori Physics Project with support from