# Why can only moving metals (aluminium) reflects a magnetic field of a magnet?

A maglev train is riding because the magnets in the train are reflecting their magnetic field on the aluminium rail, so it is lifted up. Also when you rotate a aluminium plate and you hold a magnet above it, it will reflects his own magnetic field (north or south)and is repeling it.

In a way you can compare it with looking in the mirror. You can see yourself because light is reflecting on the mirror back to you. But in case of a mirror you won't need any movement, but why is that in case of magnetic fields?

• Magnetic fields are electric fields which arise due motion due to decrease in effective distance. Given by $z= r\sqrt{1-\frac{v^2}{c^2}}$ – Anubhav Goel Feb 10 '16 at 10:11
• A varying magnetic field induces eddy currents in aluminium materials. This currents induce magnetic field which weaken the external magnetic field. BTW, the higher the speed of the plate the higher the damping (or the force you need to move the plate). – HolgerFiedler Feb 10 '16 at 10:53
• About eddy current I ask here physics.stackexchange.com/questions/234983/… – HolgerFiedler Feb 10 '16 at 11:08