The Magnetic Heat Engine, when turned on, shows
how a ferromagnet behaves if heat is
applied. The magnetism of ferromagnets is due to the spin and orbital motion of electrons about the nucleus of the atoms, making the atoms act like small magnets. The alignment of these small magnets below the Curie temperature creates a strong magnetic field. When a ferromagnet reaches its Curie temperature, the atomic magnets are not aligned anymore and it looses its magnetism. The atomic magnets point in random directions, giving the system rotational symmetry.
As it cools, the spontaneous alignment of the atomic magnets breaks the rotational symmetry and magnetism resumes when the magnet is exposed to a magnetic field.
| The Magnetic Domain Demonstrator is a representation of the same
process on the atomic scale. Visitors can create or destroy the alignment using
concept of symmetry doesn't apply solely to the arts and geometry, as
many people assume, but to the world of physics as well. Physicists
define symmetry as an "invariance of an object or system to a
This Symmetry exhibit is comprised of several activities demonstrating
symmetry and broken symmetry.
Here is a link to a Flash presentation explaining Symmetry. If the animation does not start, check that your security settings permit
running ActiveX controls and that you have Adobe's Flash Player installed on
your computer. If not, follow this link to install.
To take part in a self-guided
tour, dial 1-888-744-0529, then 20.
Broken Symmetry, the art piece, is a graphical representation of
symmetry breaking. The cover can be lifted to break the symmetry.
|The Deflecting Rod
allows visitors to break its symmetry by adding mass and causing the support rod
to bend. Symmetry can be restored by removing the mass so the rod can
Symmetry in physics