Magnetic attraction is the pull between opposite poles of two magnets or between a magnet and a magnetic material. Magnetic repulsion is the push between like poles. The strength of attraction or repulsion depends on how close the magnets are and how strong they are. Magnetic forces can act through air, water, paper, and many other materials without weakening much.
Have students explore how magnets interact through different materials (paper, cardboard, plastic, glass of water). Measure how many paper clips a magnet can hold at different distances. Race paper-clip "cars" by moving a magnet underneath a table to feel attraction through a solid surface.
You already know that magnets have north and south poles, and that opposite poles attract while like poles repel. Now let us look more closely at how attraction and repulsion actually behave. These two effects are the foundation of everything magnets do.
Attraction happens when a north pole meets a south pole — or when a magnet is brought near a magnetic material like iron. The force pulls the two objects toward each other. You can feel it in your hand when two magnets snap together. The closer the magnets get, the stronger the pull becomes. At very close distances, the force can be surprisingly powerful — strong magnets can be hard to pry apart.
Repulsion happens when two north poles or two south poles face each other. The force pushes the magnets apart. If you try to force two repelling magnets together, you can feel them slide and twist as each magnet tries to flip around so its opposite pole faces the other. The closer you push them, the harder they resist. This repelling force is exactly the same strength as the attracting force at the same distance — it just points in the opposite direction.
One amazing thing about magnetic forces is that they can pass through many materials. Place a paper clip on top of a table and slide a magnet underneath — the paper clip follows the magnet as if the table were not there. Magnetic force passes through paper, plastic, glass, water, and wood with little difficulty. It does not pass well through thick iron or steel, which is why magnetic shielding uses those metals. Understanding how attraction and repulsion work and how distance and barriers affect them lets engineers build everything from magnetic locks to high-speed maglev trains that float above their tracks.