NOTES
Chapter 15 – Making and Using Electricity
Lessson 1
STATIC ELECTRICITY: an electrical charge that builds up on an object; results from changes in matter
Matter is electrically NEUTRAL most of the time. There are equal amounts of positive and negative charges. When objects come in contact charges can be transferred. Some will have more negative charges and some will have more positive charges.
-Objects with opposite charges attract
-Objects with the same charge repel
-Lightning is caused by static electricity. Ice crystals in a cloud rub together and gain negative charge. The ground loses negative charge so it has positive charge. When the difference becomes great the negative charges move from the clouds to the ground in a giant spark-lightning!
CURRENT ELECTRICITY : a steady stream of electrons or charges. Current moves through a material such as copper wire. Current electricity is more easily controlled than static.
Power plants produce a flow of charges and send the current along wires to homes and businesses.
Circuit: the path an electric current follows (circle-no beginning or end)
For any electrical device to work the circuit must be CLOSED- charges flow around without stopping or starting.
When you close a circuit you can: start a car; star a computer ring a doorbell; use an electric mixer
A battery provides energy to the circuit. FYI- A chemical reaction inside a battery releases electrical energy ( a battery contains a metal such as zinc and a base such as manganese hydroxide. The reaction between them produces extra electrons)
ELECTRICAL CIRCUITS- CAN BE SERIES OR PARALLEL
Series Circuit: only one path for the current; a closed series circuit can light 2 bulbs
If the circuit is open at any point neither bulb will light (diagram pg. 610) A flashlight is an example of a series circuit-current flows between the battery and the bulb
Parallel Circuit: has more than one path for the electric current to follow- if something stops charges from moving along one path, they can take another. (diagram pg. 611) Homes and schools use parallel circuits-if one light goes out the others still work.
ELECTRICAL CONDUCTORS AND INSULATORS
Conductors: let electric charges through; most metals are good conductors; electrical wires are usually copper
Insulators: materials that do not let electric charges through such as rubber or plastic
Light comes from a bulb because electric current makes a thin wire inside it glow.
SWITCHES
A switch is a device that opens or closes a circuit. Turning a switch on allows two conductors to touch so the current can flow!
Turning the switch off opens a circuit- an insulator-even space filled with air- separates the two conductors
Diagram- pg. 614