Para and diamagnetic materials in magnetic field with OHP.

Para and Diamagnetic materials in magnetic field. Various paramagnetic and diamagnetic materials (about 1.5 cm. long) are suspended on a silk thread between the poles of a variable gap magnet (neodymium, very strong). Paramagnetic samples will align with the magnet poles. Diamagnetic samples will swing away from the poles. Paramagnetic samples include: aluminum (+16.5), potassium dichromate (+29.4), platinum (+201.9), and liquid oxygen (+7699). Diamagnetic samples include: copper (-5.46), carbon (-6), zinc (-11.4), silver (-19.5), lead (-23.0), and bismuth (-280.1). (The numbers are the magnetic susceptibility x 10-6 cgs). Paramagnetic materials have a net permanent magnetic dipole moment. When a magnetic field is applied, the alignment of the electron orbits in the material actually increases the field somewhat, causing the sample to align with the field. Paramagnetic materials also exhibit diamagnetism, but the paramagnetic effect is much larger. Rising temperature can destroy the paramagnetic effect, and just leave the diamagnetism. Diamagnetism is present in all materials, and is weaker than paramagnetism. When a magnetic field is applied, the electron orbits are realigned so that the magnetic field is actually weakened (an atomic-scale consequence of the Lenz law of induction), and the sample swings away from the direction of the main field.