Chapter M: Mach Number Myria

mach number

ratio of velocity of an object to the speed of sound, where

C	= velocity of sound, 1100 ft/s
M	= Mach number
V	= velocity of the object, ft/s

• Mach number, M = V/ C

MAGNETISM

pertaining to permanent magnets where metals such as hardened steel are magnetized and retain the magnetism, requiring no electricity for operation. Magnetic lines exit from the north pole and reenter the south pole of the magnet. In magnets, like poles repel and opposite poles attract, where

A	= area of pole face, cm 2
B	= flux density, gauss
D	= distance, cm
f	= magnetic flux, maxwell
F	= force, dyn
H	= field intensity, oersted
p	= pole strength, unit poles

Coulomb's law: the force between two magnetic poles is directly proportional to the product of the strength of the poles and inversely proportional to the square of the distance between the poles, as

field intensity: force per unit pole,

flux, magnetic: total number of magnetic lines in a magnetic field, as

flux density: the number of magnetic lines per square centimeter, expressed as gauss in the metric system,

force: product of pole strength and field intensity,

pole strength; strength of a pole: equivalent to number of unit poles; a distance of 1 cm from a like pole repelling it with a force of 1 dyn.

magnetism, electro

See also ELECTROMAGNETISM.

magnetomotive force

See also ELECTROMAGNETISM.

manometer