Electronics/Definitions

"Get ideas from here:"
http://en.wikipedia.org/wiki/List_of_electronics_topics
"(BUT WE ONLY WANT THINGS THAT MATTER TO A TWO YEAR LEVEL. No "quadrature amplitude modulation" or anything like that.)"
SI Units and derived units
Definitions in Alphabetical Order: 
"Another order could be definitions by subject such as DC, AC, radio, integrated circuit, etc."
to be merged.
superfluous stuff from "overview of electronics", which should be merged in with these definitions:
Charge: Particles can have three possible types of charge: positive, negative, or neutral (no charge). Electrons are negatively charged, protons are positively charged, and neutrons are (surprise!) neutral. Opposite charges tend to attract, while particles with the same charge (both positive or negative) tend to repel.
Electricity: the flow of electrons.
Electronics: is the study of gadgets that use electricity, typically creating or handling signals, not just switching power.
??? are devices which take in input, perform some function, and return some output, through the use of electricity.
Circuit: The path electrons take as they are pushed by some power source, flow through various electrical components in a gadget, and return to the power source.
Electric Field: field created by the presence of charge. The field represents the force that would be felt by a positive charge.
Voltage: Accelerates charge.
Voltage is a gravity-like potential due to the separation of a negative and a positive charge. Voltage accelerates negatively charged electrons from the negative to the positive charge, and accelerates positive charged protons and ions the other way. Pushing accelerates the charges in what is known as current.
Resistance: When moving electrons (current) collide with atoms, energy is given off as heat. Resistance is the measure of a material's tendency to cause this type of energy loss. Resistance acts to limit the flow of current due to a given voltage. As the resistance becomes infinite the current stops flowing and becomes an open circuit. When there is no resistance the circuit shorts and the current becomes infinite. (Current 'prefers' the path with the lowest possible resistance.)
Resistor: A device whose primary use is to provide resistance.
Short Circuit: there is no resistance between two points. Current flows without a change in voltage. 
Open Circuit: there is infinite resistance between two points. Current is unable to flow, but there is still a voltage between the two points.
Voltage Source creates a voltage, which creates a current. 
Current Source, which creates a current and a voltage for the current.
Voltage Drop When the current goes through resistance it loses some of the push of the voltage.
When the current comes to an intersection it has multiple paths it can take and flows according to its resistance.
Permittivity: (ε) A measure of how much energy a material absorbs in response to an electric field. Materials (εr) absorb more energy than the vacuum (ε0). The permittivity of a material is known as its dielectric constant.
Cell: Two materials with a voltage difference between them.
Capacitor: Two metal plates with a gap between them. Voltage causes charge to drain from one plate and accumulate on the other plate. This charge separation creates a voltage in the capacitor that opposes the other voltage and stops the flow of current. When a dielectric is placed between the plates it weakens the electric field between the plates and allows more charge to accumulate.
Capacitance: Any two pieces of conducting material separated by some distance have capacitance. Simply, a measure of the tendency of some configuration of metal to act as a capacitor.
Inductor: A coil of wire. Current starts to flow through the wire and creates a magnetic field. This magnetic field creates an opposing magnetic field which stops the current through the wire. Over time the inductor stops opposing current and turns into a wire.
Transformer Two connected inductors, which operate through mutual inductance. Current flows through the first inductor and creates a magnetic field that is fed to the second inductor. In response the second inductor creates an opposing magnetic field and current. Having a permanent magnet between the two inductors intensifies their magnetic fields.
Vacuum tube: An arrangement of two or more electrodes in a vacuum. Typically placed in a glass bulb to keep air from leaking in. 
Triode: The first electrical amplification device. A triode is a type of vacuum tube with three connections:
Diode: A 2 wire device that allows current to flow easily in only one direction.
Transistor: A 3 wire device, with one wire (the "base" or "gate") that controls the flow of electrons between the other 2 wires. Replaced vacuum tubes. 
Light waves: (Electromagnetic waves)