Uniform Magnetic Field. (See [Magnetic Field, Uniform].)
Unipolar. Having but one pole.
Unit. The single standard of force, light, heat, magnetism, attraction, repulsion, resistance, etc.
V
Vacuum. A space empty or void of all matter; a space from which all gases have been exhausted.
Vacuum Tubes. Tubes of glass through which electric discharges are passed after the gases have been partially removed; for example, the X-ray tube of Röntgen and the Crooke tubes.
Vibrator, Electro-magnetic. The make-and-break mechanism used on induction-coils, or other similar apparatus, in which, through alternate attractions, an arm or spring is kept in motion.
Vitriol, Blue. A trade name for copper sulphate. (Bluestone.)
Vitriol, Green. A trade name for ferrous sulphate. (Copperas.)
Vitriol, White. A trade name for zinc sulphate. (Salts of zinc.)