emf= electromotive force
I= intensity
A= ampere
R= resistance
V= voltage (same as emf)
pi= 3.141
1/2pi=1.57
Peak to Peak = 2 x peak

Peak = Peak to peak /2

Effective or RMS = .707 x peak

Peak = 1.414 x rms

average = .637 x peak
Acceptor -      A type of impurity that accepts or takes electrons from the
                atoms of a semiconductor.

Alternating Current (AC)- A current which periodically changes its direction. 

Alternating Voltage - A voltage which periodically changes its polarity.

Alternation -   One-half of a cycle, consisting of the complete rise and
                fall of an alternating voltage or current in one direction.

Alternator -    An alternating current generator.

Anode -         In a diode, the electrode that must be positive with respect
                to the cathode to allow the diode to conduct. The plate of an
                electron tube.


Armature -      That part of an electric generator in which the voltage is
                induced.

Average Value - The average of the instantaneous values through which an
                alternating voltage or current passes during one alternation.
                The average value of a sine curve is equal to .637 times
                its peak value.

Autotransformer - A transformer with a single winding.

Cathode -       In a diode, the electrode that must be negative with respect
                to the anode (plate) to allow the diode to conduct.

Capacitance -   The property of a capacitor that determines the quantity
                of electric energy that it can store.

Capacitor -     A device consisting of two conducting surfaces separated
                by an insulator and having the ability of storing electric
                energy. Also called a condenser.

Charge -        The number of electrons held on the capacitor plates. The
                act of forcing electrons onto the capacitor plates.

Charged -       The condition of a capacitor which has the full charge it
                can receive from a given applied voltage.


Coefficient of coupling (k) - A numerical rating between 0 and 1 that 
                specifies the degree of magnetic coupling between two
                circuits. Maximum coupling is 1 and no coupling is 0.

Counter Electromotive Force (CEMF) - The voltage induced in a wire by 
                self-induction which opposes the applied voltage. Also
                called back emf.

Dielectric -    The insulating material between the plates of a capacitor.

Dielectric Constant (K) - The property of the dielectric material that
                determines how much electric energy can be stored in a
                capacitor of a particular size by a value of applied voltage.

Dielectric Strength - The ability of a dielectric material of specified
                thickness to withstand high voltages without breaking down.

Diode -         Any two-electrode device that conducts in only one direction.

Discharged -    The removal of the charge in a capacitor by completing a
                circuit between the plates.

Displacement Current - The current flows in a circuit containing a capacitor
                whenever the capacitor charges or discharges.

Donor -         A type of impurity that adds electrons to the atoms of a 
                semiconductor substance.

Electric Field - A field of force that exists between positively and
                negatively charged surfaces. In a capacitor, the field is
                assumed to consist of lines of force which extend through
                the dielectric from the positive to the negative plate.

Electrode -     An element of an electron tube or semiconductor device that
                takes part in conduction, such as the plate, anode, cathode
                and filament.
Electron Emmission- The escape of electrons from certain materials.

Electron tube-  An arrangement of two or more conductive elements, enclosed
                in an envelope, to control electron flow in a circuit.

Element -       Any of the electrical parts of an electron tube such as the
                filament, cathode or plate.

Eddy Current -  Circulating current produced in connecting materials by
                a varying magnetic field. Eddy currents are undesirable in
                the core of a transformer.

Farad -         The unit of measure for capacitance. It is the capacitance
                of a capacitor in which an applied voltage of one volt will
                store a charge of one coulomb. The more practical units
                of capacitance are the microfarad and picofarad.

Filament -      In a directly heated electron tube, a heating element which
                also serves as the emitter.

Forward Bias -  A dc voltage applied to a PN junction semiconductor so that
                the positive terminal of the voltage source connects to the
                P-type material and the negative terminal to the N-type
                material. It produces forward current in the circuit.

Forward Current-Current in a circuit of a semiconductor device due to 
                conduction by majority carriers across the PN junction.

Heater -        In an indirectly heated electron tube, the element that 
                supplies heat to the cathode.
Henry (H) -     The basic unit of inductance. One henry is the inductance
                which induces a cemf of 1 volt when the current is changing
                at the rate of 1 ampere per second.

Hole -          In a crystal lattice, a point which has been vacated by an
                electron.

Hysteresis -    The lagging of induced magnetism behind the magnetizing force.


Intrinsic -     A word used to indicate a semiconductor that has no impurities.

Junction Diode- A diode consisting of a PN junction and suitable connecting
                leads.

Majority Carriers-The type of current carriers, free electrons or holes, of
                which a given semiconductor contains the most.

Minority Carriers-The type of current carriers, free electrons or holes, of
                which a given semiconductor contains the least.

N-type Semiconductor-A doped semiconductor in which the majority current
                carriers are electrons.

Peak Inverse Voltage- In an electron tube, the maximum negative voltage that
                can be applied to the plate without danger of arc-over. In
                a semiconductor diode, the maximum reverse bias voltage that
                can be applied without reaching the zener (or breakdown)
                voltage.

Plate -         In an electron tube, the electrode that must be positive with
                respect to the cathode to allow the tube to conduct. Also
                called the Anode.

Plate Current - In an electron tube, the electron flow from cathode to plate.
                In the external plate circuit, the electron flow from the plate
                through the circuit, to the cathode.

Plate Voltage-  In an electron tube, the difference of potential between
                plate and cathode.

PN Junction -   A junction between an N-type semiconductor and a P-type
                semiconductor made by some method of diffusing, fusing
                or melting.

P-type semiconductor-A doped semiconductor in which the majority current 
                carriers are holes.


Plates -        In a capacitor, the plates are the conducting surfaces.

Recombination - The action by which current carriers (electrons and holes)
                combine and cancel each other.

Rectification - The conversion of ac to pulsating dc.

Rectifier -     A device which converts ac to pulsating dc.

Reverse Bias -  A dc voltage applied to a PN junction so that the positive
                terminal of the voltage source connects to the N-type material
                and the negative terminal to the P-type material. It produces
                reverse current in the circuit.

Reverse Current -Current in a circuit of a semiconductor device due to conduction
                by minority carriers across PN junction.


Rotor -         The movable plates of a variable capacitor.

Space Charge -  In an electron tube, a cloud of free electrons surrounding 
                the emitter.

Thermionic Emission-The liberation of electrons from a solid metal as a result
                of heat (thermal energy).

Vacuum Tube-    A form of electron tube in which the envelope contains a
                vacuum, as opposed to a gas-filled electron tube, in which
                gases are pumped into the envelope after the air is removed.


Stator -        The stationary group of plates of a variable capacitor.

Temperature Coefficient (T.C.) - In a capacitor, the rating which determines
                the change in capacitance corresponding to a given change
                in operating temperature. It is usually expressed as the
                change in capacitance per unit of capacitance per degree
                Celsius.

Variable Capacitor - A capacitor in which the capacitance can be varied
                by some mechanical means.

Working Voltage - (WV) -The maximum voltage that may be applied continuously
                to a capacitor without risking breakdown.
Flux Linkage -  The linking of the magnetic lines of force with the 
                conductors of a coil. The value obtained by multiplying
                the number of turns in the coil by the number of magnetic
                lines of force passing through the coil.


Inductance -    The property of a circuit or coil that causes an electro-
                motive force to be set up due to a change of current in the
                circuit or coil.

Inductive Coupling - The coupling or linkage of two circuits by the changing
                magnetic lines of force. See also Mutual Induction.

Inductor (L) -  A coil of wire which has the property of inductance.

Laminations -   Thin layers or sheets. The term refers to the thin pieces
                of iron used to build up the core of a transformer.

Leakage Inductance - A small inductance associated with those flux lines of
               a transformer winding which are not magnetically coupled to
               the other windings of the transformer.

Mutual Inductance (M) - The ability of one conductor to induce an emf in a
                nearby conductor when the current in the first conductor 
                changes.

Mutual Induction - The electromagnetic induction produced by one conductor
                in another nearby conductor, due to the moving flux of the
                first circuit cutting the conductors of the second circuit.

Primary -       That winding of a transformer which is connected to and
                recieves energy from an external source of electrons. Also
                frequently referred to as the input winding.

Secondary -     That winding of a transformer which receives its energy
                by electromagnetic induction from the primary. Also, 
                frequently referred to as the output winding. A transformer
                may have one or more secondaries.

Self-Induction - The process by which a changing current induces a voltage
                into the conductor or coil carrying the current.

Self-Inductance - The ability of a circuit or coil to induce a voltage
                within itself.

Step-down -     This refers to a transformer that has fewer turns of wire
                in the secondary than in the primary, which causes a decrease
                or step-down of the voltage.

Step-up -       This refers to a transformer that has more turns of wire in
                the secondary than in the primary, which causes an increase
                or step-up of the voltage.

Toroid -        This refers to a circular, donut shaped core used in transformers
                Toriod cores are generally molded from powdered iron or wound
                with silicon steel strips.

Transformer -   An electric device, without moving parts, for trasferring
                electric energy from one or more circuits to one or more
                other circuits by electromagnetic induction.

Cycle -         The complete set of values through which an alternating
                voltage or current passes successively.

Effective Value - The value of an alternating current that produces the 
                same heating effect in a pure resistance as a corresponding
                value of dc. The effective value of a sine curve is equal
                to .707 times its peak value. Also called ROOT MEANS SQUARED
                (RMS) VALUE.

Electromagnetic Induction - The process of developing a voltage in a wire
                that is being either cut by or is cutting a magnetic field.

Field -         The windings of an electric generator which are supplied 
                with dc to produce the steady electromagnetic field. 
                Generators used for demonstration purposes may use 
                permanent magnets to produce the magnetic field.

Frequency -     The number of cycles of alternating voltage or current 
                which occur during a particular amount of time, usually
                one second.

Generators -    Machines used to convert mechanical energy into electric
                energy. They accomplish this by causing one or a series
                of interconnected coils to either cut or be cut by a strong
                magnetic field.

Hertz (Hz) -    The unit of frequency. One hertz is equal to 1 cycle per
                second (cps).

Instantaneous Value - The value of an alternating current or voltage at any
                specified instant in a cycle.

Inverter -      An electric or electronic device for producing alternating
                current from direct current.

Left Hand Generator Rule - A method of determining the direction of current
                flow (polarity) in a conductor, as follows: Extend the thumb
                first finger, and second finger of the left hand at right
                angles to each other. When the thumb is pointed in the
                direction (upward or downward) of conductor motion as it
                passes through the magnetic field, and the first finger is
                pointed to the south pole of the magnetic field (matching
                the direction of magnetic flux), the second finger will
                point in the direction of current flow (toward the negative
                pole or terminal).

Oscillator -    An electronic device for converting dc energy into ac energy.

Peak-to-Peak Value - The maximum voltage change occuring during one cycle
                of alternating voltage or current. The total amount of voltage
                between the positive peak and the negative peak of one cycle
                or twice the peak value.

Peak Value -    The highest or maximum value of an alternation of alternating
                current or voltage. This peak value occurs twice during each 
                cycle.

Root Mean Square (rms) Value - See effective value.

Rotor -         The rotating member of a generator.

Sinusoidal -    The graphical plot of the output of an alternator.

Slip Rings -    The rotating contacts which are connected to the loops of
                a generator.

Stator -        The stationary coils of a generator.






Magnetic Induction- The process of setting up magnetism in an object
                that is placed in a magnetic field.

Magnetic linens- The imaginary lines of force that make up a magnetic
                field.

Magnetic pole- The point at which the magnetic lines are concentrated. 
                In every magnet, there is one north pole and one south pole.

Magnetic Shield- A piece of magnetic material used to carry the magnetic
                lines around and object to prevent the object from being
                affected by the magnetic field.

Magnetism-      The property of certain materials to attract iron and
                other magnetic materials.

Magnetite       A certain type of ore which, in its natural state, has the
                property of magnetism.

Magnetomotive Force(mmf)- The force that sets up a magnetic field within
                and around an object.

Natural Magnet- A material which, in its natural state, possesses the
                qualities of a magnet. Magnetite is a natural magnet.

Permeability -  A measure of how easily magnetic lines of force can pass
                through a material.

Permanent Magnet- An artificial magnet that retains its magnetism after
                the magnetizing force has been removed. Steel, when properly
                processed, can be made into a permanent magnet.

Reluctance -    The opposition of a material to magnetic lines of force.
                Reluctance in the magnetic circuit corresponds to resistance
                in the electric circuit.

Temporary Magnet- An artificial magnet that loses its magnetism after the
                magnetizing force is removed. Soft iron is an example of a
                temporary magnet.

Tesla -         Standard unit of magnetic flux density equal to one weber
                per square meter. The previously used unit of flux density
                was the gauss, which was equal to one magnetic line per
                square centimeter.

Weber - (Wb)    Standard unit of magnetic flux measuement equal to 100,000,000,
                or 10 to the 8th power lines of force. The previously used
                unit of magnetic flux was the MAXWELL, which was equal to one
                magnetic line of force.


Zener Diode -   A junction diode designed to operate in the reverse bias region.

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