M

magnet
Body that can be used to attract or repel magnetic materials.

magnetic circuit breaker
Circuit breaker that is tripped or activated by use of an electromagnet.

magnetic coil
Spiral of a conductor which is called an electromagnet.

magnetic core
Material that exists in the center of the mahnetic coil to either physically support the windings (non-magnetic material) or to concentrate the magnetic flux (magnetic material).

magnetic field
Magnetic lines of force travelling from the north pole to the south pole of a magnet.

magnetic flux
The magnetic lines of force produced by a magnet.

magnetic leakage
The passage of magnetic flux outside the path along which it can do useful work.

magnetic poles
Points of a magnet from which magnetic lines of force leave (north pole) and arrive (south pole).

magnetism
Property of some materials to attract or repel others.

magnetizing force
Also called magnetic field strength. It is the magnetomotive force per unit length at any given point in a magnetic circuit.

magnetomotive force
Force that produces a magnetic field.

majority carriers
The conduction band electrons in an n-type material and the valence band holes in a p-type material. Produced by pentavalent impurities in n-type material and trivalent impurities in p-type material.

matched impedance
Condition that occurs when the output impedance of a souce is equal to the input impedance of a load.

matching
Connection of two components or circuits so that maximum power is transferred between the two.

maximum power transfer
A theorem that states that maximum power will be transferred from source to load when input impedance of the load equals the output impedance of the source.

Maxwell
Unit of magnetic flux. One maxwell equals one magnetic line of force.

mercury cell
Primary cell using a mercuric oxide cathode, a zinc anode and a potassium hydroxide electrolyte.

metal film resistor
A resistor in which a film of metal oxide or alloy is deposited on an insulating substrate.

metal oxide field effect transistor
(MOSFET) A field effect transistor in which the insulating layer betwen the gate electrode and the channel is a metal oxide layer.

metal oxide resistor
A metal film resistor in which an oxide of metal (such as tin) is deposited as a film onto the substrate.

meter
Any electrical or electronic measuring device. In the metric system, it is the unit of length equal to 39.37 inches.

meter FSD current
Value of meter current needed to cause the needle to deflect to its maximum position (full scale deflection).

meter resistance
DC resistance of the meter's armature coil.

mica capacitor
Capacitor using mica as the dialectric.

microphone
Electroacoustic transducer that converts sound energy into elecric energy.

microwave
Band of very short wavelength radio waves within the UHF, SHF and EHF bands.

midband gain
Gain of an amplifier operating within its bandwidth.

mid-point bias
An amplifier biased at the center of its DC load line.

mil
One thousandth of an inch (0.001 in.)

Miller's theorem
A theorem that allows you to represent a feedback capacitor as equivalent input and output shunt capacitors.

minority carriers
The conduction band holes in n-type material and valence band electrons in p-type material. Most minority carriers are produced by temperature rather than by doping with impurities.

mismatch
Term used to describe a difference between the output impedance of a source and the input impedance of a load. A mismatch prevents the maximum transfer of power from source to load.

modulation
Process by which an information signal (audio for example) is used to modify some characteristic of a higher frequency wave known as a carrier (radio for example).

monostable multivibrator
A nultivibrator with one stable output state. When triggered, the circuit output will switch to the unstable state for a predetermined period of time and then return to the stable state. A timer.

molecule
Smallest particle of a compound that still retains its characteristics.

MOSFET
Abbreviation for "metal oxide field effect transistor" also known as an "insulated gate field effect transistor). A field effect transistor in which the insulating layer betwen the gate electrode and the channel is a metal oxide layer.

moving coil microphone
Microphone that uses a moving coil within a fixed magnetic field. Dynamic microphone.

moving coil pick-up
Dynamic phonograph pick-up in which the stylus causes a coil to move within a fixed magnetic field.

moving coil loudspeaker
Loudspeaker that uses a moving "voice coil" placed within a fixed magnetic field. Audio frequency current in the voice coil causes movement which is mechanically transferred to the speaker cone. Also known as a dynamic loudspeaker.

multimeter
Electronic test equipment that can perform multiple tasks. Typically one capable of measuring voltage, current and resistance. More sophisticated modern digital multimeters also measure capacitance, inductance, current gain of transistors and/or anything else that can be measured electronically.

multiplier resistor
Resistor connected in series with a moving coil meter movement to extend the voltage ranges.

multisegmant display
Device made of several light emitting diodes arranged in a numeric or alphanumeric pattern. By lighting selected segments numeric or alphabet characters can be displayed.

multivibrator
A class of circuits designed to produce square waves or pulses. Astable multivibrators produce continous pulses without an external stimulus or trigger. Monostable multivibrators produce a single pulse for some predetermind period of time only when triggered. Bistable multivibrators produce a DC output which is stable in either one of two states. Either high or low. An external stimulus or trigger is required for the bistable circuit to change states, either high to low or low to high.

mutual inductance
Ability of one inductor's lines of force to link with another inductor.

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