thenearsightedmonkey:

Excuse me, may I blow your mind?
Drop a strong magnet on a table and it falls and lands like anything else you drop on a table. But drop the same magnet through a copper pipe and it does something spooky before it hits the table—- Just talkin’ about electromagnetic fields and Lenz’s Law, y’all!

This video was suggested by “What It Is class” member, the Five of Diamonds, who adds:

Magnets do not attract copper. That’s what the kid is trying to demonstrate in the first 5 seconds here. The relevant fact about copper is that it’s a good conductor. This just means it’s a material within which electrons can move around easily. If we think of the copper pipe not as a pipe, but instead as a stack of copper rings, it’s a little easier to understand the effect.

The closer the magnet is to any particular ring, the more ‘magnety musk ’ is within the area of that ring. Magnety musk in nerd-speak is called the magnetic field. As the magnet approaches a ring, the field strength in that particular ring is changing and changing magnety musk produces electrical musk. This relationship between electricity and magnetism is the reason for terms like electromagnetism.

Electrons move in the presence of electrical musk, so as the magnet approaches a ring, electrons in that ring of copper move around. The movement of the electrons creates a changing electrical musk, which in turn, creates more magnetic musk. So now we have magnetic musk from the magnet and magnetic musk from the moving electrons.  Loosely speaking, these musks oppose one another and slow the magnet. This happens in each ring of the stack, so the magnet falls slowly through the entire pipe.

[Note from Professor Lynda: This video is a simple demonstration of electromagnetic circuits obeying Newton’s third law which- as you remember- reads:

Actioni contrariam semper et æqualem esse reactionem: sive corporum duorum actiones in se mutuo semper esse æquales et in partes contrarias dirigi.

“To every action there is always an equal and opposite reaction: or the
forces of two bodies on each other are always equal and are directed in
opposite directions.”

I’m flying! —A.P.