China-வின் வாழ்க்கையை மாற்றிய தவளை
8 Minutes
Learn diamagnetism and magnetic levitation for students, exploring how magnets repel water and inspire space technology. A Tamil science lesson.
- Levitation of a frog and Andre Geim's experiments
- Repelling water and dropping magnets down metal pipes
- How China uses magnetic levitation for its artificial moon
What this lesson teaches
Diamagnetism is a property of materials where paired electrons create an opposing magnetic field when exposed to an external magnet, causing the material to be weakly repelled. Under an extremely powerful magnetic field, this repulsive force can lift objects containing diamagnetic materials like water, causing them to float in mid-air.
How diamagnetism works
- Inside atoms, electrons travel in pairs in opposite directions around the nucleus.
- The movement of each electron generates a small magnetic field, but the opposite directions cancel each other out to produce zero net magnetism.
- When a strong external magnet approaches, it alters electron motion and creates an opposing magnetic field.
- This induced magnetic field pushes against the external magnet, causing the material to be repelled.
Lenz law and falling magnets
When a strong neodymium magnet is dropped through a metal pipe made of aluminum or copper, it falls surprisingly slowly. Inside a plastic pipe, the magnet drops straight through at normal speed. Dropping the magnet through the metal pipe forces electrons in the metal to move and create an electric current. According to Lenz law, this induced current produces an opposing magnetic field that pushes back and slows the magnet down.
Levitating frogs and water
In 1997, physicist Andre Geim used a powerful magnetic field to make a living frog float in mid-air. Because a frog body contains about ninety percent water, the magnetic field repels the water through diamagnetism and lifts the frog. Geim received an Ig Nobel Prize in 2000 for this floating frog experiment, and later won a Nobel Prize in 2010 for researching graphene. Common diamagnetic materials include copper, gold, silver, hydrogen, and water.
China artificial moon project
China uses the science of magnetic repulsion to simulate the low gravity of the Moon. Scientists built an artificial moon facility that uses a two-foot vacuum chamber with powerful magnetic fields. By balancing Earth gravity with strong magnetic repulsion, researchers can test how instruments behave ahead of their planned crewed moon mission in 2030.