Electricity and Magnetism CHAPTER 13 Electricity and Magnetism

Electric Charges Atoms are the tiny building blocks of everything Almost all atoms have 3 different particles Positive charge (+) Negative charge (-) No charge Matter has the same amount of positive as negative

Static Electricity Charged particles move between objects that are close to each other Static electricity – happens when positive and negative charges no longer balance Static means “not moving” Moving charges create electricity They also change into sound, light, and heat energy

Storm Clouds Charged particle move between storm clouds Positive particles are near the TOP Negative particles are near the BOTTOM The static electricity is released as Lightning Lightning also creates a mighty sound – thunder

How Charged Objects Behave You can PREDICT this If two objects have opposite charges (+ & -) they will pull to each other Electric force – is the pull or push between objects that have a different charge A charged object can attract something that has no charge If two objects have same charges (+ & +) they will push away from each other

(+) (-) PULL (-) (+) PULL (+) (+) PUSH (-) (-) PUSH

+ + + -

An Electric Field Electric field – the space around electrically charged objects It is invisible But scientist will draw lines to represent it Strongest closest to the object and get weaker as it moves away A POSITIVE electric field attracts NEGATIVE charges and pushes away POSITIVE

How Electric Charges Move Electric current– electric charge in motion They flow from one place to another It travels QUICKLY and INVISIBILY The flow of electric charge is not the same in all materials

Insulators DO NOT CHARGE EASILY Electric charges move SLOWLY Plastic Rubber Glass Dry wood

Conductors CHARGED MORE EASILY MOVE QUICKLY Copper Wire Silver Most metals

Closed Circuit Circuit – a loop where electric travels DOES NOT HAVE ANY BREAKS

Open Circuit Has opening or breaks where the electricity will stop following MOVE SLOWLY Resistance – means the material does not allow electric charges to flow through it easily – the wire gives off light

Types of Circuits SERIES CIRCUIT – electric charges can flow in only ONE path Electric charges flow in a single loop All bulbs receive the same amount of energy If one bulb “burns out” it acts like an off switch NOT USED A LOT

Types of Circuits PARALLEL CIRCUITS - has two or more paths for the electric charge to flow There are little loops on the big loops Each loop is a separate path for the electric charge A break DOES NOT shut off the electric of the whole loop, just the small loop Used in homes, schools, and offices

Magnetism Magnet – anything that attracts other things made of iron, steel, and certain other metals Magnetism – is a force that acts on moving electric charge and magnetic charges that are near the magnet Magnet comes from Magnesia (a place in Turkey that was known for its magnetic materials)

Magnetic Fields Magnetic field – invisible field around the magnet, goes out in all directions Its shape depends on the shape of the magnet It is STRONGEST at the magnets “pole points”

Magnetic Poles All magnets have two poles – NORTH & SOUTH Opposite poles have opposite charges Unlike charges attract each other Like charges repel (push) IF you break a magnet in two you will then have 2 magnets with 2 poles (4 poles in total)

Largest Magnet in the WORLD Earth behaves like a large magnet Like a magnet, it has the strongest pull at its poles The Earth’s poles are no the same as the geographic poles The magnetic NORTH pole is in Canada The magnetic SOUTH pole is near Antarctica

How Compasses Work Compass – a helpful tool that help you find directions The needle will always point you in the direction of north If you are near a magnet, the compass will not work correctly

Electromagnets Invented by Hans Christian Oersted Electricity and magnetism are closely related Both are results of charged particles moving We use them a lot in our daily lives Electromagnet – is a coil of wire with many loops through which an electric current passes To make the field stronger it is wrapper around copper Can be a VERY POWRFUL MAGNET

Uses for Electromagnets Used in industry to lift heavy materials Complex machines used by doctors and scientists Are a part of many electronic gadgets: Televisions Fans DVD players Doorbell A motor Earphones

Electrical Energy This helped make electric, motors, and generators The power of magnetism can be transformed into the power of electricity This helped make electric, motors, and generators When a magnet is moved, its magnetic field moves with it Changing a magnetic field generated electricity More loops = stronger Faster = stronger

A Flashlight without batteries 1831 – Michael Faraday invented a machine that used magnets to transform motion into an electric current Turning a crank Used in emergency flashlights and radios

Currents Most homes, school, and businesses today get their electricity from generators Generator – is a machine that creates electric energy by turning coils of wire around powerful magnets Uses magnets and wires to turn mechanical energy into electrical energy

Pioneers in Electricity 1740s – Benjamin Franklin describe positive or negative 1829/1831 – Joseph Henry and Michael Faraday produce a current by changing a magnetic field 1879 – Thomas Edison created incandescent light bulb

How Generators are powered Many ways for a generator to produce electrical energy Wind power – a wind turbine changes the energy of the blowing wind into electricity Hydroelectric Power – the power of falling water is changed into electricity by generators near Niagara Falls

Electrical Safety If you are not careful, electricity can case a serious shock or start a fire Respect the power of electricity Read and follow the instructions that come with every electrical produce Replace worn or cracked electrical product Relocate, or move, appliance cords so people will not walk on or trip over them, and children or pets can’t pull them