Letter A

AIR POLLUTION - Unwanted particles, mist or gases put into the atmosphere as a result of motor vehicle exhaust, the operation of industrial facilities or other human activity.

ALTERNATING CURRENT - (AC) Flow of electricity that constantly changes direction between positive and negative sides. Almost all power produced by electric utilities in the United States moves in current that shifts direction at a rate of 60 times per second.

ALTERNATIVE ENERGY SOURCES - See RENEWABLE ENERGY.

AMPERE (Amp) - This is the unit of electrical current, often shortened to Amp. It is given the symbol "I" in calculations and can be found by dividing volts with ohms. The unit of measure that tells how much electricity flows through a conductor. It is like using cubic feet per second to measure the flow of water. For example, a 1,200 watt, 120-volt hair dryer pulls 10 amperes of electric current (watts divided by volts).

ANODE - This is the POSITIVE ELECTRODE in a circuit. It is commonly linked with DIODES in things like television sets. It is the opposite of CATHODE.

ASH - Non-organic, non-flammable substance left over after combustible material has been completely burned.

ATOM - The smallest unit of an element consisting of a dense positively charged nucleus (of protons and neutrons) orbited by negatively charged electrons.

AMNETER - An instrument used to measure electric current in amperes.

ABSCISSA - The horizontal coordinate (x coordinate) on a graph. The mathmatical name for the input of a function.