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Matter is made up of small particles called atoms. Atoms are made up of smaller, sub-atomic particles called protons, neutrons, and electrons. Sub-atomic particles have a basic property called electric charge. protons - positive charge neutrons - neutral, no charge electrons - negative charge Electric Charge and Static Electricity

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Protons and Electrons determine charge Atoms have equal numbers of protons (positive) and electrons (negative) therefore, atoms are neutral, with no charge. An atom that loses electrons will have more protons than electrons = positive charge. An atom that gains electrons will have more electrons than protons = negative charge. Electric Charge and Static Electricity

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Static electricity - the build up of electric charge due to the electrons transferring from one object to another. Electrons do not flow. Remain at rest = “static”. Methods of Charging an Object I. Friction - when an object is rubbed, it will gain or lose electrons and will gain a positive or negative charge glass rod rubbed with silk =glass rod loses electrons plastic rod rubbed with fur = plastic rod gains electrons Balloon on a person’s hair??? SILK Glass Rod - + + + + + - - - -

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Electric Charge and Static Electricity Static electricity - the build up of electric charge due to the electrons transferring from one object to another. Electrons do not flow. Remain at rest = “static”. Methods of Charging an Object II. Conduction - electrons transferred by direct contact electrons move from one object to another. conductor—a material that allows the flow of electrons. silver, copper, aluminum, mercury insulator—a material that resists the flow of electrons. rubber, glass, wood

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Electric Charge and Static Electricity Static electricity - the build up of electric charge due to the electrons transferring from one object to another. Electrons do not flow. Remain at rest = “static”. Methods of Charging an Object III. Induction - rearrangement of electrons caused by charged object placed next to neutral object. charge is “induced” when electrons move away, or attract. No contact.

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ELECTRIC CHARGE van de graaff http://phet.colorado.edu/en/simulation/balloo ns http://phet.colorado.edu/en/simulation/travolt age

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Electric Charge and Static Electricity Law of Charges- like charges repel, opposite charges attract Symbol for charge is “q” Charge is measured in COULOMB’s 1 proton = 1.602 x 10 -19 C 1 electron = -1.602 x 10 -19 C

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Electric Charge and Static Electricity Coulomb’s Law – describes the electric force between any two charges, separated by a distance “r” The force of electrical attraction between two charges is directly proportional to the product of the two charges and inversely proportional to the square of the distance between them. k = 8.9875 x 10 9 Nm 2 C 2 Many charges are expressed in micro-coulombs ( C); 1 x 10 6 C = 1 C. Easiest solution, whenever you see C, just add x 10 -6 C to the number. Ex. 5 C = 5 x 10 -6 C; 28 C = 28 x 10 -6 C

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Coulomb’s Law Example Two electrostatic point charges of 60 C and 50 C exert a repulsive force on each other of 175 N. What is the distance between the two charges? Q 1 = 60 x 10 -6 C; Q 2 = 50 x 10 -6 C.

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Electrical current is the flow of electrons. Unlike static electricity, charges are in motion. Two types of Current I. Direct current (DC) - flow of electrons in one direction. car battery, flashlight batteries, photovoltaic (solar) cell II. Alternating current (AC) - flow of electrons back and forth along a path. electric generator Electric Current

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CURRENT (I) – flow of electrons along a conductor unit: ampere (amp) 1 ampere = 1 coulomb/1sec RESISTANCE ( R ) – opposition to the flow of electrons. Electrons do work and lose energy in the form of heat. unit: ohm ( Jsec/coulomb 2 VOLTAGE ( V ) Potential Difference - energy available to move electrons from objects of high potential to objects of low potential energy. measures amount of work electrons can do if they move between two points. unit: volt (V) 1 volt = 1Joule/1 coulomb High voltage greater potential to do work. Low voltage less potential to do work. Electric Current High potential energy charged e' Low potential energy uncharged

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OHM‘S LAW - current is dependent on voltage and resistance. It is directly proportional to voltage and inversely proportional to resistance. current = voltage resistance I = V R units: amps = volts ohms The greater the voltage, the greater the current The lower the voltage, the lower the current The lower the resistance, the greater the current The greater the resistance, the lower the current Electric Current

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Circuit – path, or loop, formed by a conductor that allows electrons to flow. SERIES CIRCUIT - circuit where current travels through only one loop PARALLEL CIRCUIT - circuit consisting of several smaller circuits connected together Electric Circuits SERIES CIRCUIT - circuit where current travels through only one loop PARALLEL CIRCUIT - circuit consisting of several smaller circuits connected together SYMBOLS - Fuse - small piece of metal which melts when current is too high Circuit breaker - small piece of metal which bends when current is too high SERIES CIRCUIT - circuit where current travels through only one loop PARALLEL CIRCUIT - circuit consisting of several smaller circuits connected together SYMBOLS - Fuse - small piece of metal which melts when current is too high Circuit breaker - small piece of metal which bends when current is too high

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Circuit – path, or loop, formed by a conductor for electrons to flow. SYMBOLS - Fuse - metal in a circuit which melts when current is too high Circuit breaker - metal in a circuit which bends when current is too high Electric Circuits SERIES CIRCUIT - circuit where current travels through only one loop PARALLEL CIRCUIT - circuit consisting of several smaller circuits connected together SYMBOLS - Fuse - small piece of metal which melts when current is too high Circuit breaker - small piece of metal which bends when current is too high SERIES CIRCUIT - circuit where current travels through only one loop PARALLEL CIRCUIT - circuit consisting of several smaller circuits connected together SYMBOLS - Fuse - small piece of metal which melts when current is too high Circuit breaker - small piece of metal which bends when current is too high conductor switch (open) switch (closed) power source (battery) light bulb resistor flow

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