Electricity

Definition The flow of electrical power or charge. It is a secondary (2o) energy source, which means that we get it from the conversion of other sources of energy, like coal, natural gas, oil, and nuclear power which are all called primary (1o) sources of energy

Major Players Benjamin Franklin – kite experiment Thomas Edison – light bulb Nicola Tesla – discovered AC (alternating current) in 1879 (only direct current [DC] had been used up to that point)

Atoms Everything in the universe is made of atoms (the smallest basic unit of matter) One teaspoon of water contains about 500,000,000,000,000,000,000,000 atoms! (that’s 500 sextillion atoms – million, billion, trillion, quadrillion, quintillion, THEN sextillion)

Atoms Atoms are made of small particles called protons, neutrons, and electrons Protons (+) and neutrons (neutral – no charge) form the nucleus of the atom (the center) Electrons (-) spin around the nucleus in shells – think Saturn’s rings

Atoms The protons and electrons of an atom are attracted to each other. They both carry an electrical charge. An electrical charge is a force within the atom. When an atom is in balance, it has an equal number of protons and electrons. Opposite charges attract each other.

Static Electricity Electrons jump from one object to another For example, you walk across a carpet while wearing socks. You touch a doorknob and you get a shock because electrons jumped from the doorknob to you.

Circuits Electricity travels in circuits (closed loops) Circuit comes from the word ‘circle’ Circuits must be closed for electrons to flow

Open Closed

What is the little wire inside a light bulb called? Filament

Measuring Electricity Electricity is measured in units of power called watts Named after James Watt, the inventor of the steam engine One kilowatt = ____ watts One kilowatt = 1000 watts

Electric Charge Protons and electrons have an electric charge – a property that allows an object to exert an electric force on another object without touching it Electric force = push or pull Protons = positive (+) charge Electrons = negative (-) charge

Electric Field Def. – An area surrounding a charged object Opposite charges attract each other

Electric Field Similar (like) charges repel each other

Electric Field

Static Charge Protons and electrons have electric charges Objects and materials can also have charges Static Charge – a buildup of electric charge in an object caused by the presence of many particles with the same charge

Static Charge Some objects with high static charge:

Net Charge Def. – The total number of unbalanced positive or negative charges in an object Material with excess protons = positive net charge Material with excess electrons = negative net charge Net charge is measured in coulombs

Two Methods of Charging 1. Charging by Contact 2. Charging by Induction

Charging by Contact When two uncharged objects made of certain materials (such as rubber and glass) touch each other, electrons move from one material to the other

The balloon and the glass rod each have balanced, neutral charges + The balloon and the glass rod each have balanced, neutral charges - + - - + + - + - - + When they touch, electrons move from the rod to the balloon - - + + - + Afterwards, the net charge of the balloon is negative, and the net charge of the glass rod is positive + - - + - +

Charging by Contact Materials higher up on the list are more likely to give up electrons than materials lower on the list Skin Glass Hair Nylon (Under Armour) Wool (Socks, Sweaters) Fur Silk Paper Rubber (Balloons) Polyester

Charging by Induction If a material already has a net charge, charging by induction can occur Induction – the build up of charge without direct contact