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Glossary
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alternating current (ac) electric current in which electrons repeatedly change direction.

amperage the number of electrons that pass a given point at a given time.

ampere, amp a unit of electric current used to measure the rate of flow.

battery a device that uses chemicals to generate and store electricity.

capacitor an electric circuit element used to store charge temporarily.

circuit a path of conductors that an electric current follows.

conductor a material through which electric current flows easily.

current electricity electricity that flows through a circuit, or a continuous unbroken path.

direct current (dc) electric current that flows in one direction only.

electricity a form of energy produced by the flow or accumulation of electrons.

electromagnet a temporary magnet formed when electric current flows through a wire or other conductor.

electron a subatomic particle with a negative electrical change.

fluorescence a process by which substances give off light or another form of electromagnetic radiation when they absorb energy.

incandescence the effect by which an object begins to glow when heated.

insulator a material that opposes the flow of electric current.

ion an atom or group of atoms that has either gained or lost electrons and so has an electrical change.

ohm unit of electrical resistance used to measure a material's resistance to the flow of electric current.

Ohm's law a law stating that the direct current flowing in a conductor is directly proportional to the potential difference between its ends. It is usually formulated as V = IR, where V is the potential difference, or voltage, I is the current, and R is the resistance of the conductor.

parallel circuit a circuit that splits into branches. A break in one branch will not stop current in the other branches.

resistance the degree to which a substance resists electric current.

resistor a device used to control current by providing resistance.

series circuit a circuit that connects a source, load, and conductors in a single loop. Any break in the circuit will stop the flow of current.

static electricity the build up of electrical charges on a surface produced by the contact and separation of dissimilar materials.

superconductors materials that lose all resistance to the flow of current at low temperatures. They operate extremely fast and produce almost no heat.

transfer the movement of electrons from one place to another either by current of static.

transformation the change in energy from one type to another as in a battery, which changes chemical energy to electricity.

volt unit of potential difference (similar to pressure).

voltage a type of "pressure" that drives electrical charges through a circuit.

watt unit of power equal to volts x amps.