High powered magnets can lift cars, and steel beams as well as crush bones or break glass. In other words, magnets are capable of some incredible feats. However, there are a few things that can alter magnet strength. One of those is temperature. In our last blog we explored what happens to a magnet when it is exposed to extreme heat. Now, let’s do an experiment to explore what happens to a magnet when it is exposed to extreme cold.

Supplies

  • Plastic tongs
  • Water
  • Ice
  • Insulated gloves
  • Safety goggles
  • Thermometer
  • 2 Bar neodymium magnets
  • Dry ice (optional)
  • Insulated containers for dry ice

Steps

Part 1: Room Temperature Test

  1. Do a room temperature magnet test first. Pour the paper clips into a plastic bowl.
  2. Submerse one of the neodymium bar magnets into the bowl of clips and remove it, recording the number collected.
  3. Remove the paper clips from the magnet and set it aside. Replace the paper clips in the bowl.

Part 2: Cold Magnet Test with Ice Water

  1. Place a bowl of ice water in the freezer. Check the temperature to make sure it is around 32°F or 0°C.
  2. Put on gloves and goggles as a safety precaution.
  3. Remove the water once it is at the appropriate temperature.
  4. Carefully drop in one neodymium magnet.
  5. Replace the bowl of ice water in the freezer, leaving the magnet in for about 15 minutes.
  6. Remove the magnet from the water using plastic tongs and submerse it in the bowl of paper clips.
  7. Pick the magnet up and see how many paper clips are collected and record your findings.

Part 3: Magnet Test with Dry Ice

  1. If you want to expand your magnet experiment, you can test it in dry ice. You must wear the safety goggles and insulated gloves for this experiment! Dry ice and temperatures this cold can cause severe frostbite and burn-like effects upon contact with skin. This experiment is not meant for children and should not be conducted without protective gear.
  2. Now that you have your protective gear on, place the dry ice in the insulated bowl.
  3. With insulated gloves, position the neodymium magnet in between two pieces of dry ice. The temperature of dry ice is about -108°F or -78°C.
  4. Keep the magnet in the dry ice for about 15 minutes then remove with the insulated gloves.
  5. Place the magnet in the bowl of paper clips and record how many are collected.

Results

Magnet strength will increase with colder temperature. However, this change in magnet strength is not as dramatic as the change that comes with heat exposure. Also, as the temperature decreases the magnet strength increases but only to a certain point with NdFeB magnets. Once the magnets fall below -185°C (-301°F) a spin reorientation or a change in the magnetization direction will occur, causing the magnet strength to begin to decrease instead of increase as it did at less cold temperatures.

The Science Behind It

Magnets are made up of atoms. In normal environmental conditions, these atoms align between the poles and foster magnetism. In extremely cold temperatures the atoms will move  more slowly and less randomly. This creates a more controlled alignment of the atoms that produce the magnetic field and a slightly stronger magnetism.

If you haven’t done the experiment on magnets in heat you can find it here. For supplies, feel free to visit our inventory or contact us with any questions!

Photo by Shawn Henning