For this experiment, we used an experimental arrangement of a Gouy balance to measure the susceptibility of various samples. Our theory was that electrons have a magnetic moment that could be aligned with - or opposite - an applied magnetic field, depending on the spin of the electron(½ or ½).
In the cases where atoms or molecules with paired electrons, the individual electron contributions to the overall spin, cancel one another and give a zero net value of the overall spin number; such a species is said to be diamagnetic. When a diamagnetic substance is placed between the poles of a strong magnet, it will experience a repulsion for the applied field. This repulsion comes from the circulating electrons caused by the applied field, which in turn results in an induced magnetic field in opposition. .
In this experiment, we suspended a sample between the poles of an electromagnet that was connected to an analytical balance. This is precisely the arrangement of a Gouy balance, and as a result of the induced diamagnetic repulsion, the sample will appear to weigh less in the magnetic field compared to its true weight outside the field. .
When removed from the applied field, the sample has no residual magnetic moment, and its apparent weight will be its true weight. If a sample contains one or more unpaired electrons, the overall spin number will be greater than zero for such a species is said to be paramagnetic. If a paramagnetic species is placed between the poles of a strong magnet it will experience an attraction for the field, due to the alignment of the permanent paramagnetic moment with the applied field. If the sample is weighed with a Gouy balance, it will appear to be heavier in the magnetic field, compared to its true weight outside the field. .
So, a diamagnetic moment makes the magnet move down, and a paramagnetic moment makes the magnet move up.
