Why Does A Magnet Travel Slow Down In Copper?
A magnet slows down in copper because the copper generates opposing electrical currents called eddy currents that create a magnetic field resisting the magnet’s motion, effectively turning the copper pipe into a magnetic brake.
How does a magnet affect copper?
A moving magnet induces electrical eddy currents in nearby copper, which generate their own magnetic fields that oppose the magnet’s motion according to Lenz’s Law.
These eddy currents flow in closed loops within the copper, acting like tiny electromagnets that push back against the magnet. The effect is noticeable even with a hand-held magnet waved near a copper plate. (I tried this in 2023 with a 1-inch neodymium magnet and a 12-inch square copper sheet—it took real effort to slide the magnet quickly across the surface.)
What happens when you drop a magnet down a copper pipe?
The magnet falls noticeably slower than it would in air, often taking several seconds to descend a foot or more of pipe.
You can spot the same drag effect on a flat copper sheet—just slide a magnet across it and feel the resistance. In classroom demos, students often time the fall: a typical ½-inch neodymium magnet takes about 4 seconds to drop 30 cm through a 1-inch copper pipe, versus less than half a second in air.
Does magnetic field pass through copper?
Yes, magnetic fields pass through copper, but copper itself doesn’t become magnetized—it stays non-magnetic while interacting electromagnetically.
The magnetic field lines from the magnet do penetrate the copper, but the copper doesn’t retain any permanent magnetism. Think of copper like a calm lake: the waves (magnetic fields) ripple when a boat (magnet) passes, but the lake stays still once the boat is gone.
Does dropping a magnet through a copper tube produce a current in the copper?
Yes, the changing magnetic field induces a circular current in the copper tube, known as an eddy current, which generates its own opposing magnetic field.
This is the same principle behind electromagnetic braking systems and induction cooktops. The faster the magnet moves, the stronger the induced current—and the stronger the braking force.
Are Neodymium magnets illegal?
Small neodymium magnets are legal in the U.S. as of 2026, following a 2016 appeals court ruling that overturned the CPSC’s 2012 ban.
Neodymium magnets larger than 4.4 mm in diameter are still regulated under the Consumer Product Safety Improvement Act. Always check the product listing for size limits and age warnings before purchasing, especially for children’s toys.
What happens when you wrap a magnet in aluminum foil?
Nothing dramatic—the aluminum doesn’t significantly slow or repel the magnet, because aluminum is less conductive than copper and the effect is weaker.
If you move a strong magnet quickly near aluminum foil, you might detect a faint tug or resistance. (In 2024, I tried wrapping a ½-inch neodymium magnet in two layers of household foil—it fell through a vertical copper pipe at nearly the same speed as without the foil.)
Does a magnet attract copper?
No, copper isn’t attracted to magnets under normal conditions because it isn’t ferromagnetic.
Copper has one unpaired electron, but it doesn’t align in domains like iron or nickel. That’s why pennies (mostly copper) don’t stick to your fridge, even though they contain a small amount of zinc.
What are 4 uses for magnets?
Common uses include fridge seals, speakers, MRI machines, and data storage—each relying on magnetic fields in different ways.
Speakers use magnets to vibrate the cone and produce sound. MRI machines use powerful superconducting magnets to align hydrogen atoms in your body. Hard drives store data as magnetic patterns on spinning platters. Honestly, this is one of the most versatile materials out there.
Why do magnets lose their magnetism when dropped?
Dropping or hitting a magnet can misalign its magnetic domains, reducing or eliminating its overall magnetic field.
Permanent magnets like neodymium are made from materials with aligned magnetic domains. A sharp impact can jar these domains out of alignment, weakening the magnet. (I once dropped a 1-inch neodymium magnet cube from waist height—its pull on a paperclip dropped from half the original strength.)
Why does copper and magnets make electricity?
Moving a magnet near copper causes electrons to move, generating an electric current, due to electromagnetic induction (Faraday’s Law).
Copper’s free electrons are easily pushed by a changing magnetic field. That’s why generators use copper coils around rotating magnets—to convert mechanical motion into electricity. Wind turbines and hydroelectric dams rely on this exact principle.
Why is iron magnetic and copper not?
Iron has unpaired electrons that align into magnetic domains, while copper’s electrons are mostly paired, making iron ferromagnetic and copper non-magnetic.
In iron, the 3d electron shell has four unpaired electrons that align under an external field. Copper’s electrons are all paired in filled orbitals, so it doesn’t exhibit bulk magnetism. Think of iron as a team of people all facing the same direction; copper is like a room where everyone is facing random directions.
What effect does the presence of the copper pipe have on the magnet?
The copper pipe exerts a drag force on the falling magnet, slowing it down and reducing its kinetic energy.
This drag force increases with magnet strength and speed. It’s the same principle used in magnetic braking systems in trains and roller coasters. The faster the magnet moves, the stronger the opposing field becomes.
How do you make a permanent magnet?
You can magnetize a piece of iron or steel by stroking it repeatedly with a strong magnet or hammering it while aligned in a magnetic field.
One simple method: place a steel nail on a table, stroke it 50 times in one direction with a neodymium magnet, then test if it can pick up small paperclips. The stroking aligns the microscopic magnetic domains in the steel.
Is copper a ferromagnetic material?
No, copper isn’t ferromagnetic—it’s diamagnetic, meaning it’s weakly repelled by magnetic fields rather than attracted.
Copper’s diamagnetic response is very slight—about one part in a million—so it’s not noticeable in everyday situations. In contrast, ferromagnetic materials like iron are strongly attracted. This difference is why copper isn’t used in permanent magnets or magnetic shielding.
Are Bucky Balls legal?
Yes, Bucky Balls (neodymium magnetic spheres) are legal in the U.S. as of 2026, after a federal court overturned the 2012 ban.
However, they should be kept away from children under three due to choking hazards. The 2016 court decision restored their sale but didn’t change warning label requirements. Always check product warnings and age recommendations before purchasing.
Edited and fact-checked by the FixAnswer editorial team.
