Mathematics and Physics Glossary

Back bearing, n. (Nav.) Same as Reciprocal bearing.

Baily's beads (Astron.) A row of bright spots observed in connection with total eclipses of the sun. Just before and after a total eclipse, the slender, unobscured crescent of the sun's disk appears momentarily like a row of bright spots resembling a string of beads. The phenomenon (first fully described by Francis Baily, 1774 -- 1844) is thought to be an effect of irradiation, and of inequalities of the moon's edge.

Balance n.

1. (Phys.) A state of equilibrium or parity characterized by cancellation of all forces by equal opposing forces.

2. (Math.) Equality with respect to the net number of reduced symbolic quantities on each side of an equation.

3. (Astron.) (a) The constellation Libra. (b) The seventh sign in the Zodiac, called Libra, which the sun enters at the equinox in September.

Band, n. (Phys.) (a) A specific range of wavelengths or frequencies of electromagnetic radiation. (b) A range of very closely spaced electron energy levels in solids, the distribution and nature of which determine the electrical properties of a material.

Barad n. (Phys.) The pressure of one dyne per square centimeter; used as a unit of pressure.