Magnetic force is created by the movement of electric charge. Every magnet, from a refrigerator magnet to the Earth itself, ultimately gets its power from electrons in motion. These electrons generate tiny magnetic fields that, under the right conditions, combine to produce the push or pull you can feel between two magnets or watch deflect a compass needle.
Where Magnetism Starts: Inside Atoms
Magnetism begins at the atomic level with electrons doing two things at once. First, electrons orbit the nucleus of an atom, and that movement creates a small loop of electric current. Any loop of current produces a magnetic field, so each orbiting electron acts like a microscopic magnet. Second, every electron has a property called “spin,” a built-in rotation that generates its own magnetic field independent of the orbit. Together, these two sources give each electron a magnetic moment: a tiny force with a north and south pole.
In most atoms, electrons are paired so that their magnetic moments cancel each other out. That’s why most materials aren’t magnetic in any obvious way. But in certain elements, like iron, cobalt, and nickel, some electrons are unpaired. Their magnetic moments don’t cancel, leaving each atom with a net magnetic field. This is the raw material that makes strong magnets possible.
How Atoms Team Up to Make a Magnet
Having magnetic atoms isn’t enough on its own. A plain iron nail has trillions of magnetic atoms, yet it doesn’t stick to your refrigerator. The reason is that inside any ferromagnetic material, atoms organize into regions called magnetic domains. Within each domain, the atomic magnetic moments line up parallel to each other, creating a strong local field. But in an unmagnetized piece of iron, these domains point in random directions, and their fields cancel out. The overall magnetization is zero.
When you bring an external magnetic field near the material, the energy balance shifts. Domains whose magnetic direction already points roughly along the external field start to grow, expanding at the expense of domains pointing the other direction. The boundaries between domains, called domain walls, physically move through the material. At stronger fields, the walls get swept out entirely and the remaining domains rotate to align precisely with the field. At that point the material is “saturated,” and you have a strong permanent magnet. Remove the external field and some of that alignment persists, which is why you can magnetize a nail by stroking it with a magnet.
The Force Between Magnets
Once you have two sources of magnetic field, the interaction between them is what you feel as magnetic force. Every magnet is a dipole, meaning it has a north pole and a south pole. Opposite poles attract, like poles repel. This happens because the magnetic field lines flowing out of one magnet’s north pole naturally curve toward a nearby south pole, and the system reaches a lower energy state when the magnets come together in that configuration. Flipping one magnet around forces the field lines to compete, pushing the magnets apart.
The strength of this force drops off rapidly with distance. For a magnetic dipole, the field falls as the cube of the distance. Double the gap between two magnets and the force drops to roughly one-eighth of what it was. This steep decline is why a magnet that feels powerful against your fridge barely tugs at a paperclip from across a table. It’s also why magnetic force, despite being one of the fundamental forces of nature, has a relatively short practical range.
What Magnetic Fields Do to Moving Charges
The deeper rule behind all magnetic interactions is surprisingly simple: magnetic fields only exert force on charges that are moving. A stationary electric charge sitting in a magnetic field feels nothing. But the moment that charge starts moving, it experiences a force that is perpendicular to both its direction of travel and the direction of the magnetic field. This principle is described by the Lorentz force law, and it has a crucial consequence: a magnetic field can change the direction of a moving charged particle but never its speed. The force is always sideways, never pushing the particle faster or slowing it down.
This is why charged particles spiral in magnetic fields rather than accelerating in straight lines. It’s also the operating principle behind electric motors, where current-carrying wires sitting in a magnetic field experience a sideways push that creates rotation. Generators work the same way in reverse: moving a wire through a magnetic field pushes the charges inside it, generating electric current.
Electric Current Creates Magnetic Fields
The connection between electricity and magnetism runs in both directions. Just as magnetic fields push on moving charges, moving charges create magnetic fields. A straight wire carrying electric current produces a magnetic field that circles around the wire. The strength of that field is directly proportional to the current and inversely proportional to the distance from the wire.
Coil that wire into a loop and the field lines concentrate through the center, making the field stronger. Stack many loops together into a coil (called a solenoid) and the field inside becomes remarkably uniform and strong, proportional to both the current and the number of loops per unit length. This is how electromagnets work, and it’s the principle behind MRI machines. A clinical MRI scanner typically uses a 1.5 or 3.0 tesla magnet, roughly 50,000 to 100,000 times stronger than Earth’s magnetic field at the surface, which ranges from about 22,000 to 67,000 nanotesla depending on location.
Why Some Materials Respond Differently
Not all materials react to magnets the same way, and the differences come down to electron structure. Materials fall into a few broad categories based on their magnetic behavior.
- Ferromagnetic materials (iron, cobalt, nickel) have strong interactions between their atomic magnetic moments that force them into parallel alignment. These are the materials that make permanent magnets and are strongly attracted to magnetic fields. Iron loses its ferromagnetic properties above 770 °C, cobalt above about 1,121 °C, and nickel above 358 °C. These thresholds, called Curie temperatures, are the points where thermal energy overwhelms the alignment forces and the material becomes only weakly magnetic.
- Paramagnetic materials (aluminum, platinum, certain salts) have unpaired electrons that give individual atoms a magnetic moment, but those moments don’t interact strongly with each other. Place a paramagnetic material in a field and the atoms partially align, creating a weak attraction. Remove the field and the alignment vanishes instantly.
- Diamagnetic materials (copper, water, bismuth, most organic matter) have no unpaired electrons at all. When exposed to an external field, the orbiting electrons adjust slightly in a way that produces a tiny opposing field. Diamagnetic materials are very weakly repelled by magnets. This property exists in all matter but is so faint it’s usually masked by stronger paramagnetic or ferromagnetic effects.
Why Magnets Always Have Two Poles
One of the most fundamental facts about magnetism is that every magnet has both a north and south pole. Cut a bar magnet in half and you get two smaller magnets, each with its own north and south pole. You can never isolate a single magnetic pole. This stands in stark contrast to electricity, where positive and negative charges exist independently.
Physicists have searched for isolated magnetic poles, called magnetic monopoles, for over a century. Experiments at CERN’s Large Hadron Collider have looked for them in high-energy particle collisions using both proton-proton and heavy-ion data, with no signal found. For now, magnetism remains strictly dipolar: every magnetic field traces a continuous loop from north to south, with no beginning or end point. This is one of the cornerstones of electromagnetic theory and part of what makes magnetic force behave so differently from electric force at every scale, from atoms to planets.