Mho.
A unit of conductance, not in very general use. It is the reciprocal of
the ohm. Thus a resistance of ten ohms is a conductance of one-tenth
mho.
Mica.
A natural mineral, a silicate of several oxides; muscovite. It is used
as an insulator and dielectric. Its resistance per centimeter cube after
several minutes electrification at 20º C. (68º F.) is 8.4E13 ohms
(Ayrton). Its specific inductive capacity is 5, air being taken at 1.
Mica, Moulded.
An insulating material, whose body is made of mica pulverized and
cemented together with heat and pressure and some suitable cement.
Shellac is often used as the cement.
Micro.
A prefix meaning "one-millionth of;" a micro-farad is one-millionth of a
farad.
Micrometer.
An instrument for measuring small distances or small differences. It
generally is based upon an accurate screw which may have a worm wheel
for head, actuated by a worm or helix with graduated head, so that
exceedingly small advances of the screw may be produced. The pitch of
the screw being known its actual advance is known.
Micrometer, Arc.
A micrometer for measuring the distance between voltaic arc electrodes.
Micron.
A unit of length. It is one-millionth of a meter or four
one-hundred-thousandths of an inch.