Lodestone. The scientific name is magnetite. Some samples possess polarity and attract iron; these are called lodestones.
Loop. A portion of a circuit introduced in series into another circuit.
Low Frequency. A frequency (in current vibrations) of comparatively few alternations per second.
Low Potential Current. (See [Current, Low Potential].)
Luminescence. The power or properties some bodies have of giving out light when their molecular mass is excited. For example, phosphorus and radium.
Luminous Heat. The radiation of heat by electric current, which at the same time produces light. For example, the filament in an incandescent lamp.
Luminous Jar. A Leyden-jar whose coatings are of lozenge-shaped pieces of tin-foil between which are very short spaces. When discharged, sparks appear all over the surface where the small plates of metal nearly join.
M
Magnet. A substance or metal having the power to attract iron and steel.
Magnet-bar. A magnet in the shape of a straight bar. (See [Bar-magnet].)