https://www.youtube.com/watch?v=DCaN59knUCk

Electricity – movement electrons in a material Moves best through metalsStatic electricity - collection of electrons & positive ions on surface of a non-conductor D.C. moves in one direction usually is created in batteriesA.C. -most commonly used in homes & can have its voltage changed as needed

Static ElectricityUsually produced by gathering a group of stationary electronsElectron have a _________ chargeEx: When you walk on carpet & drag your feet, the ________ that takes places b/t your shoes & the carpet causes a build up of static electricityThen you get a shock when you touch something metal

Electrons = – charge_______ = + chargeOpposites charges attract each otherCharges that are alike (two + or two –) repel each otherConservation of charge = ?Charges are conserved just like energy is conserved (charges are transferred)

Conductors – material which electric charges can flow through easily (Ex: metal)Best conductors?Highest to lowest: silver, copper, aluminum, iron, silicon, water, glass, StyrofoamIf H2O is not a top conductor- why not swim during a lightning storm?

Insulator – material which electric charges cannot flow through easily or maybe not at all (Ex: plastic, rubber, wood)Electrical cords are coated with plastic or rubber - you should not use a cord where the coating is damaged – you touch it & get shocked or it touches carpet or curtain & starts a fireStatic Elec. can only accumulate on insulators

Induction – an object’s electric field causes electrons to move to another object in close proximity (not touching)Conduction – an object shifts some of its electrons to another object b/c they touchedElectric Discharge – when electrons jump from a charged to an uncharged objectEx: Lightning

Voltage, Resistance, & CurrentOhm’s Law – in ideal conductors, voltage is proportional to current & this relationship is expressed as a constant called resistanceV = I RV is the voltage in volts I is the current in amperes or amps R is the resistance in ohms

Voltage - electrical potential energy, measured in volts Think of a water hose = There is water pressure or potential energy on the other side of the faucet. Once you open the faucet, the pressure causes the water to rush through the hose.Current - indicates amount of electrons passing through the wire, measured in amperes or amps, A, as in 2.0A. Electrical current is similar to the rate of water flowing through a hose. Resistance - can be thought of as the "friction" on the movement of electrons in a wire. Measured in ohms, omega, Ω. Three ohms is written as 3 Ω.Resistance is similar to the friction inside the hose. But also, the resistance increases with a narrower hose, just like a thin copper wire has more electrical resistance than a thick wire.

If voltage increases, current also increases (assuming resistance stays the same)

Electronic devices have resistorsEx: Toaster – the heating element is a piece of wire w/ greater Ω than copper. When the current gets to the wire heating element, the Ω increases & the current slows down, so the wire gets hot (looks orange-red) & toasts the bread!

Watt ratings on light bulbs indicate how much power they need to workPower – the rate at which electrical energy is supplied (measured in watts)In simple circuits, Power is directly related to product of voltage & currentP = V I Power = volts • amps

If a toaster has 120 volts & 2.3 amps, what is the Ω of the heating element?R = V / I = 120 V / 2.3 A = 52 Ω

If the toaster is plugged into a standard wall outlet (120 volts) which supplies a current of 6A, how much power does the toaster use?P = VI = 120 V • 6A = 720 W

All electronic devices use circuitsCircuits are paths for electric current to flow throughCircuits are created by combining material w/ different conductivity (best conductors?)

Electrical CircuitsSwitches – the use it to turn something on or off – it does this by opening or closing a circuitOff = open circuit (incomplete) current can’t flow through the circuitOn = closed circuit (complete) current can flow through it2 types: Series & ParallelSeries is basically a loopIf any part of the series fails, everything is cut off

Complex series circuit – has more than 1 resistor in the circuitResistance increases each time a resistor is added& current decreasesI = V / RR = inversely proportional to IRtotal = R1 + R2

Add up the resistors to find total resistanceTotal voltage must = current needed for the sum of all resistorsVtotal = I • Rtotal

Parallel circuit – resistors are wired so there are alternate paths to follow if 1 resistor fails Christmas tree lights are like this – if 1 light goes out the rest stay litYour house is like this or else all the power would go off when you turned off 1 switch

ElectromagnetismMagnetism – general term for forces of attraction & repulsionMagnetic field – where we notice these forcesElectromagnet is made when electric current runs through a wire loop that is surrounding an iron coreStrength of the magnet is directly related to # of coils wrapped around the core

Mostly used in stereo speakers, electronics, motors & generatorsMotor – converts electric energy into mechanical energy (ex: mixer)Generator- converts mechanical energy into electrical energy (ex: post storm)

Magnetic poles act like electric charges (poles called N & S)Opposites attract & like repel

CompassEarth has a magnetic fieldActs like a huge bar magnet runs through the center from N to S polesNot exactly geographic N & S poles (these are in line with the axis Earth spins on)

Compass points toward magnetic North

http://www.kingsford.org/khsWeb/rfs/elemsci/circuit.html

http://www.kingsford.org/khsWeb/rfs/elemsci/circuit.html  Series and Parallel Circuit Labitems neededAluminum Foil, small Christmas tree lights cut off a string of small Christmas tree lights with end of wire striped, 6 to 9 volt battery pack or power source, alligator clip wires, tape, scissors (Note if you do not have the alligator clips on the wire you can make a connection by wraping the bare wire in the foil. Lights for this experiment Battery pack - the pack can lack the aligator clips. If you donot have them, wrap the foil around the bare wire. you can find the parts to make this at Radio Shack - You moight have to let them know in advance to have enought battery packs to do this with a class. Do not use a 9 volt battery. they go dead to fast in this experiment to be of value to you Notes Parallel and Series Circuit. One the student have cut out the foil pattern. they should connect the foil to the wire on the bulb by pushing the foil around the wire. Hook up the battery. Then disconnect a bulb . The other bulbs in the parallel circuit will stay on as there is another pathway for the electricity to flow. In the series circuit the lights will go out as there is only one way for the electricity to flow through the circuit.

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