demonstrations:diamagnetism_of_water

Diamagnetism of Water

Materials: ★★☆ Available in most school laboratories or specialist stores
Difficulty: ★☆☆ Can be easily done by most teenagers
Safety: ★☆☆ Minimal safety procedures required

Categories: Magnetism

Alternative titles: Water and Magnetic Repulsion

Summary

Water is diamagnetic, meaning it creates a weak magnetic field opposite to an applied external magnetic field. This property can be demonstrated by the slight repulsion of water from a strong magnet.

Procedure

  1. Fill a glass with water and place it on a stable surface.
  2. Bring a very strong magnet (e.g., 12,200 gauss or stronger) close to the side of the glass.
  3. Observe carefully as the water is very weakly repelled, causing a small but detectable effect. Reflecting grid paper from the surface of the water can help to show this.
  4. Discuss how the induced magnetic field in the water opposes the applied field.
  5. Extend discussion to stronger field demonstrations: with magnetic fields greater than 10 Tesla, even small animals (like frogs) can levitate because their bodies are mostly water (lookup videos of this).

REPELLING WATER - ENGLISH - Water is diagmatic and can be repelled by a magnet - Arvind Gupta:


Diamagnetism of Water - Ludic Science:


📄 The diamagnetism of water - auris: https://www.aurismagnetic.com/en/content/52-the-diamagnetism-of-water

Variations

  • Try the experiment with other diamagnetic materials such as copper, zinc, bismuth, or glass and compare effects.
  • Test paramagnetic materials (like aluminum) to observe how their behavior differs from diamagnetism.
  • Use superconductors to demonstrate stronger diamagnetic levitation effects (the Meissner effect).
  • Compare weak water repulsion with ferromagnetic attraction for contrast.

Safety Precautions

  • Handle very strong magnets with care to avoid pinching injuries.
  • Keep magnets away from electronic devices, bank cards, and medical implants.
  • Do not attempt living-animal levitation demonstrations in a classroom, as they require extremely powerful magnets (over 10 Tesla) and specialized facilities.

Questions to Consider

  • Why does water repel from a magnet instead of being attracted? (Because water is diamagnetic, it induces an opposing magnetic field.)
  • Why is the effect so weak in everyday experiments? (Diamagnetism in water is very weak compared to ferromagnetism, requiring very strong fields to see noticeable effects.)
  • Why can frogs be levitated in extremely strong magnetic fields? (Their bodies are mostly water, and the induced diamagnetism opposes gravity when the magnetic field is strong enough.)
  • Why can’t we levitate humans with classroom magnets? (The required magnetic fields—tens of Tesla—are far beyond the strength of ordinary magnets and would need large laboratory setups.)
  • How does diamagnetism differ from ferromagnetism? (Diamagnetism produces a weak repulsion in all materials, while ferromagnetism produces strong attraction in certain materials like iron, cobalt, and nickel.)