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ELECTRICITY Explain Atomic Structure Review p+ - nucleus no - nucleus e- - electron cloud atoms have a neutral charge net charge of “0” atoms become charged by gaining or losing electrons IONS – charged atoms + or Electroscope – instrument used to detect electric charge. Atoms can gain or lose electrons based on their environmental conditions. Static Electricity – excess electric (having extra electrons) in an object ◦ Feet on carpet ◦ Balloon on hair Electrically charged objects follow a set of rules: 1. Law of Conservation of Energy (Charge)Charges may be transferred but not created or destroyed. 2. Opposite charges attract. Like charges repel. Think MAGNETS. 3. Charges act at distances. (Because of electric field). Objects closer together (shorter distance) will have a greater attraction. Objects farther apart (greater distance) will have a lesser attraction. 4. Electrons move more easily through conductors. 5. Electrons are inhibited by insulators. Transferring Electric Charge Happens by Contact – touching, rubbing Induction – closeness to something of opposite charge. (balloon close to shirt) Static Discharge – transfer through air (electrons built up in air) EX: lightning Grounding – using a conductor to direct an electric charge to the ground. EX: lightning rods Electric Current -flow of electrical charges through a conductor -electrical charges are…….ELECTRONS -conductor is made of……….METAL -current is measured in amperes (A) Remember: Electrons are IN EVERYTHING!! They simply need a path and a push to move. Charges (e-) flow from high voltage to low voltage -Voltage DIFFERENCE is what causes charges to “flow” (push) -Voltage (the push) is measured in Volts (V) -Current flow must happen in a CIRCUIT - a closed path on which electrons travel Resistance – tendency for a material to “oppose” the flow of electrons. -will change electrical energy into thermal energy and/or light. -all materials have some electrical resistance -measured in Ohms ( Ω ) -making wires thinner, longer or hotter increases the resistance. Ohm’s Law: the current in a circuit = the voltage difference / the resistance. I = V/R I (current) labeled in Amperes Electrical Circuits: circuits rely on generators at power plants to create a voltage difference at an outlet (plug-in) wall socket – voltage difference across the two holes of an electrical outlet. when the circuit is “complete” or “something is plugged in,” the charge can move from high to low. Series Circuit one loop current is the same at any part of the circuit Interrupting (opening) the circuit will cause the whole thing to turn off EX: x-mas lights (old) Parallel Circuit multiple loops current can flow to individual parts of the circuit interrupting (opening) the circuit will not affect the whole unit electrical system in a house x-mas lights (new!) Household Electricity: -standard voltage difference generated by outlets ~120V – regular outlet -tv, microwave, phone charger, clock, vacuum ~240V – high power outlet -washer, dryer, oven, camper/rv Electricity enters your home at…….. a fuse box or a circuit breaker, then branches out to your sockets and lights. Objective of the fuse box or circuit breaker: guards against electric overheating. Electrical energy is easily converted into mechanical, thermal, or light. Electrical Power: (remember power is a rate) ~rate at which electrical energy is converted into another form of energy. labeled W – Watts or kW – kilowatts P = IV Calculating energy: kWh – kilowatt hour E = Pt