All matter is made up of atoms atoms are made up of protons,

electrons and neutrons Protons and electrons can transmit

energy in the form of electricity When 2 different materials are brought

into close contract some electrons move to the other material

Causes the material to become electrically charged (positive charge or negative charge)

Negatively charged-more electrons, less protons

Positively charged-more protons, less electrons

Static electricity is produced from the buildup of positive and negative charges

Principles of Electricity: Opposite charges attract Like charges repel

When a charged balloon is brought near a wall, its extra negative charges repel the negative charges on the wall

The negative charges move to the other side of the wall

The wall becomes positively charged The balloon has a negative charge

causing it to be attracted to the wall and stick

Conductors: Electrons move through a material

easily Can cause a spark Ex: human tissue touching metal

doorknob

Insulators: Electrons do not flow easily through a

material Ex: human tissue touching plaster will

not cause an electric spark

It is dangerous to touch a bare wires Grounding wires of an appliance

connects the metal case to the ground through the household wiring

If a dangerous charge builds up the grounding wire enables the appliance to share the change with the ground

Grounding wires protect us from getting dangerous shocks

Produced by static electricity Negative charges build up in a cloud The ground has a positive charge When enough negative charges build

up they form a path to the ground Surge of electric energy heats the air to

glow-we see lightning Heat makes the air expand rapidly-we

hear thunder Lightning has high electric energy,

which is deadly

A path along which charged particles can travel

Electrons move through the wires and bulbs Consist of a source of electricity, devices

and connecting wires The source of electricity starts pulling and

pushing on the electrons and the electrons start flowing to the positive end of the source

A flow of charged particles moving through a circuit is called a current

Electrons move from negative to positive

Sources of electricity are rated by voltage As the voltage becomes greater, more

negative and positive charges can build up at one end

Resistor-opposes a flow of electrons It makes the current smaller by opposing

the flow of electrons The lamp could blow out without the resistor The resistor reduces the current of electrons

flowing through the lamp to a safe level

Short circuit could occur if the current is not reduced

If the current is not reduced, electrons will collide causing the wires to heat up

This heat could cause a fire

Only one path for the electric current Their voltages are added together Increased crowding of electrons at the

negative end of one battery Increased removal of electrons at the

positive end of the other battery Puts more force on electrons in the wires

and bulbs, which produces more current Light bulbs act as a resistor to prevent a

short circuit from occurring The flow of charges is the same at any

point

More than one path for current Electricity source makes each path feel

the same overcrowding of electrons Total current increases when another

path is added, even though another resistor is present

Current in each path depends on the strength of its resistor

Currents are added together to find the total current

Total current is the same at any point

Incomplete circuit Switch is in the off position There is no current Electrical devices do not receive

electric energy Copy circuit 1 in Notebook

Complete path for a current Current flows in the wires and devices Current transfers energy to the device Switch is in the on position or closed Copy Circuit 2 in Notebook

Attract metal objects made of iron, cobalt or nickel

Attract and repel other magnets Have 2 poles: north-seeking pole and a

south-seeking pole South pole of one magnet repels the

south pole of another A north magnetic pole attracts a south

magnetic pole The attraction is strongest at the poles

Magnetism comes from the motions of electrons in atoms

Moving electrons cause atoms to line up in the same direction

Permanent magnets-atoms always stay lined up

If brought near and object that is nonmetallic, there is no attraction

Devices that are made magnetic by an electric current

Magnetism results from moving electrons in a current-carrying wire

If brought near a nonmetallic object, there is no attraction

Is the area around a magnet in which other magnets can feel attraction or repulsion

Magnetic force moves from the north pole to the south pole and form closed loops

Attraction or repulsion is strongest where the arrows are most crowded

Tilt of Earth’s axis causes the magnetic poles to be off true geographic north and south poles

Magnetic field is not evenly shaped Compass needle always points to the

magnetic north pole Earth’s magnetism is likely caused by

electrical currents in a fluid metal layer around Earth’s inner core

Used to power toys, elevators, fans, air compressors, cranes, some cars and bicycles

The spinning force comes from an electromagnet

A loop of wire is placed between 2 permanent magnets

When current passes through the wire, the loop becomes an electromagnet

Magnetic resonance imaging (MRI) Strong magnetic field produced by

electromagnets cause the nuclei in the patients body to behave like magnets and line up with the magnetic field

This enables radio waves to produce images of tissues inside the body

Speakers depend on electromagnets to operate

Cone in a speaker has an electromagnet

Current passes through the electromagnet causing the cone to vibrate and produce sound

A device that produces a current in a solution

Use chemical reactions to produce an electric current

Charged particles always move in the same direction-direct current

Consists of 2 different metal plates in a solution

Produces a voltage-the difference in the amount of potential energy between the plate

Voltage is measured in volts

The amount if current can be measured by an ammeter and the unit is ampere or amp

Produce an electric current using a moist conducting paste

Chemical reactions between the paste and the plates produce a current

Ex: battery

Uses mechanical energy to make electricity

It produces an alternating current Electric power plants use generators to

produce electricity for homes and businesses

Transformers are used to increase or decrease the voltage of the current

Electric current produced by huge generators

Power lines connect the power plants to homes in cities and towns

Electric current from a generator first passes through a transformer that increases the voltage anywhere from 120,000 to 500,00 volts

Before the current comes into our homes it passes through another transformer that decreases the voltage

Household circuits use 120 volts The total current for an entire house is

100 or 200 amps You can run two appliances on the

same circuit, which has 20 amps, as long as they do not use more amps combined

Short circuits occur when too much current flows through a wire

Fuses and circuit breakers protect homes from catching on fire

Any form of energy can be changed into other forms

Electrical energy can be changed into 4 other types of energy

1.Mechanical Energy Electric energy changes into

mechanical when any device that uses a motor is used

Examples: food blenders, electric fans, power tools

2. Heat Coils get very hot because of an

electric current Electrons from the current collide with

the atoms in the coils Temperature of the coils rise Ex: heaters, electric blankets, toasters,

hair dryer3. Sound Current causes electromagnets to

move a diaphragm back & forth producing sound waves

Ex: speakers

4. Light 2 types of light bulbs1. Incandescent Contain a thin metal wire or filament

that acts like a resistor Electric current heats it causing the

filament to give off heat and visible light

Only 12% of the energy is light Rest of energy is wasted as heat

2. Fluorescent Produce more light than heat Series of collisions causes gas inside

the glass to produce light Fluorescent coating on the outside

glows