AC power plug Standard way of accessing electricity in various parts of a building.   Wikipedia         

Alternating Current (AC) The flow of current will change direction. Can be transformed to step up or step down the voltage. Favored by Nikola Tesla.  Wikipedia         

American Wire Gauge (AWG) Standard for wire sizes   Wikipedia         

ampere (amp) (A) 1 coulomb per second.            

Amplitude Modulation (AM)    Wikipedia         

analog    Wikipedia         

André-Marie Ampère The SI unit of current, the ampere, is named after him.   Wikipedia         

antistatic wrist strap Equalize the electrical charge between a person and the equipment.   Wikipedia  Netacad       

Autotransformer Have only one winding used as both the primary and secondary. At a disadvantage by not having line isolation between the windings.            

British Thermal Unit (BTU) Amount of heat required to raise the temperature of 1 pound of water 1 degree Fahrenheit.            

capacitance Generally rated in farads (F), microfarads (μF), nanofarads (nF) or picofarads (pF). To find the total:

connected in parallelvalues add
connected in seriesreciprocal method

capacitor Oppose a change of voltage. Capacitance determined by:

Stores energy in an electric field. Current flows only while the capacitor is charging or discharging. Charge and discharge at an exponential rate.   Wikipedia  YouTube (Make:)       

constant-current transformer (aka: current regulators) Generally used to provide power to series connected loads.            

coulomb Measure of charge.            

current (I)    Wikipedia         

dielectric Insulating material used in capacitors.   Wikipedia         

Direct Current (DC) Current goes only one direction. Favored by Thomas Edison.  Wikipedia         

doping Adding impurity atoms to a semiconducting material. Can be p-type or n-type.   Wikipedia         

electromotive force (EMF) (Voltage or Potential difference)            

Electrostatic discharge (ESD) When built up static electricity transfers form one object to another. Can damage computers and other electronics. Increased likelihood in low humidity.   Wikipedia  Netacad       

flux Lines of flux repel each other and never cross.            

frequency The number of complete cycles in one second. Measured in hertz.            

Frequency Modulation (FM)             

henry (H) 1 volt-second per ampere. Symbolized by 'L'   WikiHow         

hertz (Hz) SI unit of frequency. One cycle per second.   Wikipedia         

horsepower (HP) (1 hp = 550 ft-lb/s, 1 hp = 746w) Average horse can do 550 foot-pounds of work per second.             

impedance    Wikipedia         

induced voltage Proportional to the change rate of current. Always opposite in polarity of the applied voltage.            

inductance (L) Measured in henrys (H). One of the primary types of load in AC circuits.   Wikipedia         

inductive reactance (XL) Counter-voltage that limits the flow of current, as does resistance. Measured in ohms. Proportional to inductance of a coil and the frequency of the line.            

inductor Coil of wire wrapped around a core, such as iron. Generates an electromagnetic field. Developed by Michael Faraday in 1831 when he discovered electromagnetic induction.  Wikipedia  YouTube (Make:)       

isolation transformer Primary and secondary windings are electrically and mechanically separated. Help filter voltage and current spikes between the primary and secondary side.            

jumper Can close or open a circuit.    Wikipedia         

Light Emitting Diode (LED) Anode (+ long positive lead). Cathode (- short negative lead). Discovered by H. J. Round in 1907. Popularized by Nick Holonyak in 1962.  Wikipedia  YouTube (Make:)       

maxwell One magetic line of force.            

metal-oxide-semiconductor field-effect transistor (MOSFET) Type of transistor.   Wikipedia         

MKS system of units    Wikipedia         

mutual induction When a coil induces voltage into another coil.            

NEMA Connector Standard AC power plug used in North America.   Wikipedia  NEMA Chart  NEMA Plug & Receptacle Configurations     

ohm (Ω) (R) Unit of resistance. Named after Georg Ohm.   Wikipedia         

peak Maximum amount of voltage attained by a waveform.            

peak-to-peak Amount of voltage measured from the positive-most to the negative-most peak.            

polarity dots Schematic symbol used to indicate polarity.            

pure inductive circuit Voltage and current are 90° out of phase.            

pure resistive circuit Current and voltage are in phase.            

quality (Q) Determined by the amount of resistance compared with the inductive reactance.            

resistance (R)    Wikipedia         

resistor Resists the flow of electricity.     YouTube (Make:)       

root mean square (RMS) (aka: effective value)


scalar Indicates magnitude only.   Wikipedia         

self induction When a coil induces voltage into itself.            

Semiconductor    Wikipedia         

sine wave The most common AC waveform. 360° in each cycle. Voltage at any point along the waveform is equal to the peak (max) value × the sine of the angles of rotation. The average value is used when an AC sine wave is changed to DC.   Wikipedia         

step-down transformer Lower secondary voltage than primary voltage.   Wikipedia         

step-up transformer Higher secondary voltage than primary voltage.   Wikipedia         

tone generator Sends a tone through the length of a cable.   Wikipedia  Netacad       

toner probe Used to trace the location of a cable. Can find a cable when a tone generator is atached to one end.   Wikipedia  Netacad       

transformer    YouTube (Make:)         

transformer Among the most common electrical devices. Can change the values of voltage, current and impedance but cannot change the frequency.


transistor    Wikipedia  YouTube (Make:)       

vector Lines that indicate both magnitude and direction.            


volt-ampere reactive (var) (aka: quadrature power, wattless power) Amount of reactive power in the circuit.


volt-amperes (VA) Apparent power in a circuit.


voltage (V)    Wikipedia         

watt (W) Measurement of true power. SI unit of power.


weber (Wb) SI unit of magnetic lines of flux. 1 Wb = 100 million lines of flux. Named after German physicist Wilhelm Eduard Weber.  Wikipedia         

XL = 2πfL