[align=left]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 magnetic coil to either physically support the windings (non-magnetic material) or to concentrate the magnetic flux (magnetic material).
magnetic field
Magnetic lines of force traveling 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 source 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.
****l film resistor
A resistor in which a film of ****l oxide or alloy is deposited on an insulating substrate.
****l oxide field effect transistor
(MOSFET) A field effect transistor in which the insulating layer betwen the gate electrode and the channel is a ****l oxide layer.
****l oxide resistor
A ****l film resistor in which an oxide of ****l (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 dielectric.
microphone
Electroacoustic transducer that converts sound energy into electric 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.)
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.
monostable multivibrator
A multivibrator 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.
moving coil pick-up
Dynamic phonograph pick-up in which the stylus causes a coil to move within a fixed magnetic field.
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 continuous pulses without an external stimulus or trigger. Monostable multivibrators produce a single pulse for some predetermined 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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N
n-type semiconductor
A semiconductor compound formed by doping an intrinsic semiconductor with a pentavalent element. An n-type material contains an excess of conduction band electrons.
negative
Terminal that has an excess of electrons.
negative ground
A system where the negative terminal of the source is connected to the system’s ****l chassis.
negative ion
An atom having a greater number of electrons in orbit than there are protons in the nucleus.
negative resistance
A resistance such that when the current through it increases the voltage drop across the resistance decreases.
negative temperature coefficient
A term used to describe a component whose resistance or capacitance decreases when temperature increases.
neon bulb
Glass envelope filled with neon gas which when ionized by an applied voltage will glow red.
network
Combination of interconnected components, circuits or systems.
neutral
A terminal, point or object with balanced charges. Neither positive or negative.
neutral atom
An atom in which the number of negative charges (electrons in orbit) is equal to the number of positive charges (protons in the nucleus).
neutral wire
The conductor of a polyphase circuit or a single-phase three wire circuit that is intended to have a ground potential. The potential difference between the neutral and each of the other conductors are approximately equal in magnitude and equally spaced in phase.
neutron
Subatomic particle in the nucleus of an atom and having no electrical charge.
nickel-cadmium cell
A secondary cell that uses a nickel oxide positive electrode and a cadmium negative electrode.
node
Junction or branch point in a circuit.
noise
Unwanted electromagnetic radiation within an electrical or mechanical system.
An operational amplifier circuit having no phase inversion between the input and output.
non-inverting input
The terminal on an operational amplifier that is identified by a plus sign.
non-linear scale
A scale in which the divisions are not equally spaced.
normal closed
Designation which states that the contacts of a switch or relay are closed or connected when at rest. When activated, the contacts open or separated.
normally open
Designation which states that the contacts of a switch or relay are normally open or not connected. When activated the contacts close or become connected.
north pole
Pole of a magnet out of which magnetic lines of force are assumed to originate.
Norton’s theorem
Any network of voltage sources and resistors can be replace by a single current source in parallel with a single resistor.
notch filter
A filter which blocks a narrow band of frequencies and passes all frequencies above and below the band.
npn transistor
A bipolar junction transistor in which a p-type base element is sandwiched between an n-type emitter and an n-type collector.
nucleus
Core of an atom. The nucleus contains both positive (protons) and neutral (neutrons) subatomic particles.
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