For Young Scientists · Exhibit 1

The Magic of the
Invisible Push

No hands. No strings. Something else.

Slide a magnet under a table. A paperclip on top starts to move — all by itself. Nothing's touching it. It just goes. This moment has a name. It's called a field. And it's everywhere.

We don't watch you. We just want you to wonder.
Discovery 1

Something is
pushing and pulling — through things.

When Eugene was young, his father slid a magnet under a thin table. A paperclip on top started following it around — without touching it. It moved through the wood.

Not through a hole. Not by accident. The force reached through solid matter. That's the part that should make you stop and say: wait — what?

That feeling is the right reaction. It's the same one that made humans curious enough to figure out compasses, generators, and eventually the internet. It all starts with a paperclip that shouldn't move.

The Tabletop

Move the magnet under the table. Watch what happens above.

Move your mouse (or finger) over the canvas — the magnet follows

Move the magnet close to the paperclip. What do you notice?
Discoveries 2–7

Seven things
worth knowing

Discovery 02
Why does it work through the table?
Magnetic fields don't care about most materials. Wood, paper, cardboard, your hand — the field passes right through them. It only stops (well, slows) for materials that are themselves magnetic — iron, nickel, cobalt. That's why you can do this trick with a thin table but not a thick steel plate.
Discovery 03
Why does the paperclip move and a piece of paper doesn't?
A paperclip is made of steel — mostly iron. Iron has something special inside it: tiny magnetic regions called domains. Normally they point every which way and cancel out. But when a magnet gets close, most of them snap into line with the field. Suddenly the whole paperclip becomes a little magnet. And magnets attract. Paper has none of this. The field passes through it and nothing happens.
Discovery 04
What happens when you flip the magnet?
Every magnet has two poles — north and south. Opposites attract, like poles push apart. When you flip the magnet, the pole facing the paperclip switches. The paperclip still gets attracted — because it re-aligns its domains for whatever pole is closest. But if you had two paperclips already magnetized and facing the same pole? They'd push each other. That repulsion is the harder feeling to trigger — and the more useful one.
Discovery 05
Why does the force weaken with distance?
Magnetic force follows an inverse-square law: double the distance, and the force drops to roughly one quarter. A thick table isn't just more wood — it's a gap that eats the field rapidly. This is why fridge magnets slide off if you hold them a centimetre away. The field is still there, but too weak to hold. Closeness is everything.
Discovery 06
Can you stack paperclips? Why?
Yes — and it gets stranger. When a paperclip attaches to a magnet, it becomes magnetic. So a second paperclip can attach to the first one. And a third to the second. You're building a chain of temporary magnets. Remove the original magnet and most of the clips fall — the iron domains scatter back to random. Some iron "remembers" a little — that's called remanence, and it's how you make a permanent magnet.
Discovery 07
What happens if you spin the magnet?
A spinning magnet creates a changing magnetic field. And here's the discovery that changed everything: a changing magnetic field creates an electric field. Michael Faraday figured this out in 1831. He called it electromagnetic induction. Every electric motor, every generator, every power plant on Earth runs on this one idea — spin a magnet, get electricity. The paperclip trick scaled up is civilization.
It's Everywhere

Three things you've used
today that run on this

🧭
The compass
Earth is a giant magnet — its molten iron core creates a field that stretches into space. A compass needle is a tiny magnet that aligns with Earth's field. North is just "where the south pole of Earth's magnetic field points." Explorers navigated continents with this.
🔋
Every motor and generator
The fan in your laptop, the vibration in your phone, the engine in an electric car — all of them are spinning magnets near coils of wire, using Faraday's discovery. Your phone charger converts spinning-magnet electricity back into the kind that charges batteries.
🏥
MRI machines
An MRI scanner is a supercooled magnet so powerful it can align the hydrogen atoms in your body. Then it sends radio waves. The atoms respond differently in different tissues. The machine reads that response and builds a 3D image of your insides — no surgery required.
Magnetic Field Lines

The field has shape — you just can't see it.

Magnetic fields aren't just "stronger near the magnet" — they have a specific geometry. Field lines emerge from the north pole, loop around, and re-enter at the south pole. They can't cross each other. The closer the lines, the stronger the field. This isn't a metaphor — it's what iron filings sprinkled on a piece of paper reveal directly.

Ferromagnetic Domains

Iron remembers. Sort of.

At the atomic scale, electrons spin — and spinning charge creates a tiny magnetic field. In most materials, these fields cancel out. In ferromagnetic materials (iron, nickel, cobalt), quantum mechanics forces neighbouring electrons to spin in the same direction, creating magnetic domains — regions up to a millimetre across where all the atomic magnets point the same way.

Unmagnetized iron
Domains point randomly — fields cancel. Net result: no magnet.
Near a strong magnet
Domains snap into alignment. The whole piece becomes magnetic.
Faraday's Law

Moving field = voltage. Every time.

Faraday's law of electromagnetic induction (1831): a changing magnetic flux through a loop of wire induces an electromotive force (voltage) in that loop. Written as ε = −dΦ/dt — voltage equals the rate of change of magnetic flux. The negative sign (Lenz's law) tells you the induced current opposes the change that caused it.

This is why stationary magnets don't generate electricity — the flux isn't changing. It's the movement that matters. Spin the magnet, change the flux through the wire coil continuously, get continuous voltage. Scale this up to a turbine and you have the power station.

Maxwell unified this with electric fields in 1865: changing magnetic fields create electric fields, and changing electric fields create magnetic fields. This mutual creation propagates as an electromagnetic wave at the speed of light — because light is an electromagnetic wave. The paperclip on the table is the same physics as sunlight.

References
  • Griffiths, D.J. (2017). Introduction to Electrodynamics. 4th ed. Cambridge University Press. (Chapters 5–7)
  • Feynman, R.P., Leighton, R.B., & Sands, M. (1964). The Feynman Lectures on Physics, Vol. II. Caltech. feynmanlectures.caltech.edu
  • Faraday, M. (1832). Experimental Researches in Electricity. Philosophical Transactions of the Royal Society, 122, 125–162.
  • Kittel, C. (2004). Introduction to Solid State Physics. 8th ed. Wiley. (Chapter on ferromagnetism and domains)
  • NASA. Earth's Magnetic Field. nasa.gov
  • Nave, R. HyperPhysics — Magnetism. hyperphysics.phy-astr.gsu.edu
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