Diamagnetism is a magnetic property first discovered in 1778 by Dutch scientist Sebald Justinus Brugmans. He discovered the property while using bismuth and antimony and realized they were repelled by magnetic fields. It wasn’t until 1845 that English scientist Michael Faraday named the property diamagnetism while studying elements and compounds that exhibited negative magnetism, meaning they were pushing away from the magnet. In layman's terms, diamagnetism is a property that every element possesses, which causes a weak repulsion from a magnetic field. In contrast, some elements also possess ferromagnetism and paramagnetism, which causes them to be strongly attracted or repulsed by the magnetic field.

To show diamagnetism, you can use a DIY magnet experiment with a common everyday food, grapes, to show small repulsion when exposed to a strong rare earth magnet. This experiment will only work with neodymium magnets because of the strong magnetic field they produce.    

Supplies

Directions

  1. Tie one end of the string to the middle of the straw.
  2. Attach the other end of the string to your fixture or the edge of a desk with the tape. Be sure that the stand allows the string to spin the straw circularly.
  3. Push each grape onto the ends of the straw. You may need to push one grape further into the straw depending on the weight. You want the straw to stay level when not in motion.
  4. Bring the magnet close to the grape without touching. Watch as the magnet pushes it slowly away. Now turn the magnet so that the opposite polarity faces the grape. Does the grape still push away from the magnet?

Because the magnet pushes the grape away regardless of the polarity, we know the grape is diamagnetic. Materials that are diamagnetic are repelled by both magnetic poles because the electrons pair with electrons of the opposite spin.

Now you may be wondering why the grape is diamagnetic, well, it’s because grapes are mainly made of water, which is diamagnetic. Other common compounds that are diamagnetic are items like wood, petroleum, and some plastics.

Using this material, you can now test other everyday objects that might possess the property of diamagnetism. Let us know in the comments section if you find any items we should try as well!

Image by Tribp