Demonstration of Lenz Law

Moving metal past a magnet (or vice versa) induces an electric current that acts as a brake on the motion. Various metals have different conductive properties and will fall past magnets at different speeds. Some like aluminum are very conductive, and others like a nickel-zinc allow have bad conduction and hardly slow at all.

Category:

Howto & Style

Tags:

• magnets
• lenz
• law
• magnetic
• braking

[pcdsgh]

the reliability of this demonstration relies on a single thing: if a copper coin moves as fast/faster than an iron coin with the same surface, then this whole experiment is a fake. (each coin on a magnet)

Copper is a better conductor than iron.

What I think I saw is metal coins simply being attracted to the magnet, increasing the friction between them, thus decreasing the speed, not the actual lenz effect.

This experiment should also be very difficult to measure without complex machinery.

[ianorg]

None of the coins were magnetic. If they were even slightly attracted to the magnets they would have simply stuck to them and not moved at all. An iron disk would have flown out of my fingers before I could even drop it.

Lenz law is easy to demonstrate with todays strong rare earth magnets.

[Rapppit]

No one has explained why the nickle was not effected in the same way as the other coins; any scholars of Maxwell out there?

[ianorg]

It's due to resistance. The less resistance a metal has the more powerful the effect is. The alloy that nickels are made of has high resistance so it is not slowed down much. The oversized couns are made from aluminum which is both light and very conductive, so they drop very slowly.

[ianorg]

Thats fun too but way harder to film. :-)

[Nabo00o]

Those coins acts just like a coil by creating eddy currents. That is a bunch of electrons that wanders in a circle as the magnetic field changes. This in return creates a magnet field of opposite polarity, resisting the coins motion.

[panamabob100]

@machinationu the later dated pennies after 1983 are zinc not aluminum

[LilReaper1010]

use a gold coin next.....that would work well ^^

[thinkstrait]

@Rapppit copper is a lot more conductive than nickel it has a higher charge density "n" in the formula I=nvqA this determines the current passing through it since the n is bigger in copper the I is bigger by the same factor resulting in a higher electric field and a higher magnetic feild and that is why copper is more affected by it than nickel :D

[pixphi]

@ianorg Aluminum isn't all that conductive, it's very far from Copper.

[machinationu]

some "pennies" are steel or aluminum, Not copper as they are just plated.

cut one in half and look at it, some are magnetic also (iron)

[mikesteel5000]

@pcdsgh

US coins are non magnetic.

[64298]

Which metal has good conductance and will slide past a magnet easily? Can I find wire made of this metal?

[solarsynapse]

The silver coins have a copper center. The nickel is...mostly nickel and is NOT magnetic, like good stainless steel.