Magnets are fascinating, and they can be created in a few different ways. You can make a magnet by running an electric current through a wire, finding a material where all the magnetic fields of its atoms are naturally aligned, or by forcing the magnetic fields of atoms to align. But did you know there’s another type of magnetism that all materials exhibit, even if their atoms aren’t magnetic? It’s called diamagnetism, and it’s pretty cool, even though it’s quite weak compared to other types of magnetism.
Diamagnetism occurs when an external magnetic field causes the electrons around the atoms in a material to change their paths. This new motion generates a magnetic field that opposes the external one. Although this opposing field is weak, it causes the material to be slightly repelled by the magnet. For instance, if you hang a wooden toothpick in a magnetic field, the ends will repel the field, causing it to align across the magnetic field.
The term “diamagnetism” is easy to remember because “dia” means across, like the diameter of a circle. So, diamagnetic materials will repel a magnet, and a diamagnetic “compass” will point across the magnetic field, orienting east/west.
Despite its weakness, diamagnetism is pretty amazing because it creates a repulsive effect. Any diamagnetic material can levitate in a strong enough magnetic field! Imagine a chunk of graphene or even a frog levitating because water is diamagnetic. In theory, humans could also levitate this way, but the magnetic fields needed would be enormous.
There are some interesting details about diamagnetism. For example, nitrogen is diamagnetic even though its atoms have unpaired electrons, which might make you think it should be at least paramagnetic. However, nitrogen atoms bond to form N2 molecules with full outer electron shells, making them only diamagnetic. On the other hand, molecular O2 still has unpaired electrons, making it paramagnetic.
You might have also seen how superconductors can levitate in a magnetic field. This is a kind of perfect diamagnetism. Not only do the currents in a superconductor create opposing magnetic fields, but they also expel magnetic fields from the material entirely. However, the root cause of this phenomenon is quite different, and that’s a story for another day.
So, the next time you think about magnets, remember that even the weakest form of magnetism, diamagnetism, has some pretty awesome effects!
Gather materials such as graphite or bismuth and a strong magnet. Try to levitate the diamagnetic material above the magnet. Observe the repulsion and discuss why this occurs. Document your findings and share them with the class.
Use a wooden toothpick and a strong magnet to create a simple diamagnetic compass. Hang the toothpick in the magnetic field and observe how it aligns across the field. Explain the science behind this phenomenon in a short presentation.
Investigate how superconductors exhibit perfect diamagnetism. Prepare a presentation on how superconductors work, their applications, and how they differ from regular diamagnetic materials.
Research the magnetic properties of different elements, focusing on why nitrogen is diamagnetic and oxygen is paramagnetic. Create a visual chart to compare and contrast these properties, and present your findings to the class.
Imagine a world where humans can levitate using diamagnetism. Write a short story exploring the possibilities and challenges of such a world. Share your story with classmates and discuss the scientific principles involved.
Magnetism – A physical phenomenon produced by the motion of electric charge, resulting in attractive and repulsive forces between objects. – Magnetism is responsible for the operation of devices like electric motors and generators.
Diamagnetism – A form of magnetism that occurs in materials that are repelled by a magnetic field and do not retain the magnetic properties when the external field is removed. – Bismuth and copper are examples of materials that exhibit diamagnetism.
Electrons – Subatomic particles with a negative charge, found in all atoms and acting as the primary carrier of electricity in solids. – The flow of electrons through a conductor is what constitutes an electric current.
Magnetic – Relating to or exhibiting magnetism, typically involving the attraction of iron and other metals. – The magnetic properties of iron make it useful in creating electromagnets.
Repel – To push away or resist, often used in the context of magnetic forces where like poles push away from each other. – Like poles of two magnets will repel each other, while opposite poles attract.
Materials – Substances or matter from which something is or can be made, often studied in physics for their properties and interactions. – Scientists study different materials to understand their conductivity and magnetic properties.
Fields – Regions of space characterized by a physical quantity, such as gravitational or magnetic influence, that affects objects within the region. – Magnetic fields are visualized using field lines that show the direction and strength of the force.
Levitate – To rise or cause to rise and hover in the air, typically by means of magnetic forces or other physical phenomena. – Superconductors can levitate above a magnetic track due to the Meissner effect.
Nitrogen – A chemical element with the symbol N and atomic number 7, commonly found in the atmosphere and used in various scientific applications. – Liquid nitrogen is often used to cool superconductors to very low temperatures.
Superconductors – Materials that can conduct electricity with zero resistance when cooled to critical temperatures. – Superconductors are used in MRI machines due to their ability to create strong magnetic fields without energy loss.
