Torsion balance helps identify ferro-, dia- and paramagnetic materials

Abstract

A neodymium magnet mounted on a torsion balance was placed near samples of ferro- dia- and paramagnetic material held in a plastic container. Similar experiments have used a cotton thread (with no restoring torque) and a pencil as the balance to allow students/pupils to detect the magnetization of many household commodities such as water, Blue-tac, fruit and salt. The present work uses a metallic wire as a suspension which provides a restoring torque due to the elasticity in the wire. Thus, a measurable deflection can be observed when the magnetic and torsion forces balance. For aluminium, the initial negative deflection is a manifestation of Lenz’s law.