Magnetic properties of copper.

Copper itself is not magnetic or only slightly magnetic (not strong enough to see this in normal situations). But it interacts with magnets, and this is very important. It is this interaction with magnets that power plants use to generate the electricity we use every day.

Magnetism and electricity are closely related. When a magnet moves near copper (or other metals), it sets up electrical eddy currents.

Eddy currents will repel the magnet when it hits the copper tube. This repulsion pushes the magnet and slows it down.