The Glossary
Note:  If you know a term that should be added on this page, type up the correct definition and email it to me.  I welcome your suggestions.

Term

Definition
Frequently Asked Questions  Check here for some great reading!  This section will grow throughout the year.  So keep checking back.   

 Amperage

 Not a correct term, see current.  

 Ampere

Amp (A) for short.  The Amp is the unit of current flow.  We measure current by the Amp.  1 ampere is 1 coulomb (C) of electrons moving past a point in a circuit every second.  If two coulombs of electrons move past a point in a circuit every second, the current in the circuit would be 2 amperes or 2A.    

 Capacitor

A device that stores charge.  Think of a capacitor as acting like a bucket that can not be overfilled.  Capacitors can be charged up and then discharged.  Just like a bucket can be filled up and later emptied out.   

 Charge

A group of electrons all gathered up somewhere.  The more the electrons, the bigger the negative charge.  We measure charge by the Coulomb.  1C = 6.25 X 1018 electrons for a negative charge or the same amount of protons for a positive charge.  

Conductor

A material that allows current to flow through it.  All metals are good conductors.  Touching a bare conductor that is connected to a voltage source can be very dangerous and could cause electrocution.   Never touch a conductor that is connected to a voltage source larger than 12V.  It could be dangerous!  

 Current

Current is the flow of electrons.  Electrons have a negative charge and move from the negative side of a voltage source to the positive side.  Current can not flow in a circuit unless there is a complete (unbroken) path for them to move through.  Current

 Diode

A device that lets current pass in only one direction.  Transistors have two very specially designed diodes inside them.  

 EMF

EMF stands for Electromotive Force which is a voltage.  A battery voltage can be referred to as an EMF.  Typically this term is related to the voltage generated in a wire when the wire is cut by a magnetic flux line.  A back voltage, or Back EMF is generated inside a rotating motor which reduces its current when the motor is running fast.  
Frequency Frequency, as it relates to AC voltages, is how many pulses or cycles in one second's time.  If you listen closely to a battery operated clock with a second hand, you will hear one tick every second.  One tick every second is also called one cycle per second or one Hertz.  Named after a scientist, the Hertz is the unit of frequency.  Two ticks every second would be two Hertz and so forth.  When a telephone rings, the frequency is 20 Hz.  or twenty Hertz.   The higher the frequency the higher the pitch of the sound. 
Inversely Proportional Take a look at the Ohm's Law formula. 

R stands for resistance, V stands for voltage, and I stands for current.  Since the R is below the line, an increase in resistance causes the current to be lower.  In fact, if the resistance is doubled in a circuit, the current will cut in half.  Because of this relationship we say that the current in a circuit (I) is inversely proportional to resistance (R).  As R increases, I will decrease. 
See also:  Proportional and Ohm's Law  
Audio Experiment:  Get a pencil and paper and click here.  500Kb

 Magnemotive

 Force (MMF)

MMF stands for Magnemotive Force.  

This term deals with electromagnets.  

MMF = A x T  or amps times the number of turns in the coil of wire.  MMF is the potential to produce magnetic flux.  (((Covered in depth Edison Project 7)))

 Ohm's Law

Ohm's Law describes the relationship between Voltage, Current and Resistance.  Ohm's Law is expressed here as a formula.  I, stands for current, V stands for voltage and R stands for resistance.    

See also:  proportional and inversely proportional

Proportional Look at the Ohm's law formula. 

You will notice that the V is on top in this formula.  If the V (voltage) is increased, the current in the circuit will also increase.  If the voltage doubles in a circuit, the current will also double.  This relationship is called directly proportional or just proportional for short.
See also:  Inversely Proportional and Ohm's Law
Audio Experiment:  Get a pencil and paper and click here.  400Kb

Reciprocal

The reciprocal of a number is found by dividing 1 (one) by the number you wish to find the reciprocal of.  

Example:  The reciprocal of 4 is 1/4. 

The reciprocal of a fraction is found by inverting the fraction (i.e. turning it upside down).  

 

Example: The reciprocal of 5/4 is 4/5.
 
Scientific calculators often have a reciprocal key, which looks like this:  "1/x"  or it may be X-1

 Resistance

Opposition to current flow.  Resistance holds back on current and decreases the amount of current flow.  You can think of a resistor as a pinch in a water hose.  The pinch restricts the current flow of water just like a resistor restricts the flow of electrons in a circuit. More resistance means less current can flow.  Resistance

 Resistor

A device that holds back the flow of current.

Series Circuit

A series circuit is a circuit that has only one path for current to flow.  

Series String

A series string is a small part of a big complex circuit that is like a series circuit.  Two or more components in a circuit that share the same exact current flow are in a series string with each other.  If you remove one of the components in a series string the devices in that series string will not have any current flow through them either. 

 Transistor

A three terminal device that can be used to amplify small signals and make them louder.  Transistors are also used as switches to turn things on or off.  

 Voltage

The push or pull that causes current to flow. More voltage means more current.   Voltage

The glossary is a great idea suggested and co-authored by Joseph O'Connell.