Why do magnets fall more slowly through a copper tube?
When you move a magnet past a metal plate or through a copper tube you generate a current*.
If we drop a non-magnetic piece of metal down the copper tube it is unaffected, but the in the case of the magnet it aligns it’s self with the tube generating current.
This is also how you convert mechanical energy into electrical energy as one might charge their headlight on their bike. But why is it moving more slowly?
The current it’s self generates magnetic fields which oppose the magnetic field generated by the magnet impeding it’s movement.
The key is in explaining that the law* runs both ways; current generates magnetic fields, and magnetic fields generate current.
*This is known as Lenz’s law.