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Electricity & Magnetism Static, Currents, Circuits Magnetic Fields & Electro Magnets Motors & Generators

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Atoms… Have neutrons, protons, and electrons. Have neutrons, protons, and electrons. Protons are positively charged Protons are positively charged Electrons are negatively charged Electrons are negatively charged

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Electrons… Are located on the outer edges of atoms…they can be moved. Are located on the outer edges of atoms…they can be moved. A concentration of electrons in an atom creates a net negative charge. A concentration of electrons in an atom creates a net negative charge. If electrons are stripped away, the atom becomes positively charged. If electrons are stripped away, the atom becomes positively charged.

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+ - + + + + The world is filled with electrical charges: + + + + + - - - - - - - - -

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What is this electrical potential called? Static Electricity Static Electricity -- - - - - - + + + + +

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Static Electricity The build up of an electric charge on the surface of an object. The build up of an electric charge on the surface of an object. The charge builds up but does not flow. The charge builds up but does not flow. Static electricity is potential energy. It does not move. It is stored. Static electricity is potential energy. It does not move. It is stored.

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Static Discharge… Occurs when there is a loss of static electricity due to three possible things: Occurs when there is a loss of static electricity due to three possible things: Friction - rubbing Friction - rubbing Conduction – direct contact Conduction – direct contact Induction – through an electrical field (not direct contact) Induction – through an electrical field (not direct contact)

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Conductors vs. Insulators Conductors – material through which electric current flows easily. Conductors – material through which electric current flows easily. Insulators – materials through which electric current cannot move. Insulators – materials through which electric current cannot move.

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Examples Conductors: Conductors: Metal Metal Water Water Insulators: Insulators: Styrofoam Rubber Plastic Paper

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Electricity that moves… Current: The flow of electrons from one place to another. Current: The flow of electrons from one place to another. Measured in amperes (amps) Measured in amperes (amps) Kinetic energy Kinetic energy

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What is Current? Electric current is the flow of electrons through a wire. Electric current is the flow of electrons through a wire. Current is measured according to the number of electrons that pass a given point in a second. Current is measured according to the number of electrons that pass a given point in a second. The symbol for current is I. The symbol for current is I.

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There are 2 types of currents: Direct Current (DC) – Where electrons flow in the same direction in a wire. Direct Current (DC) – Where electrons flow in the same direction in a wire.

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There are 2 types of currents: Alternating Current (AC) – electrons flow in different directions in a wire Alternating Current (AC) – electrons flow in different directions in a wire

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What is Resistance? The opposition to the flow of an electric current, producing heat. The opposition to the flow of an electric current, producing heat. The greater the resistance, the less current gets through. The greater the resistance, the less current gets through. Good conductors have low resistance. Good conductors have low resistance. Measured in ohms (Ω). Measured in ohms (Ω).

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What Influences Resistance? Material of wire – aluminum and copper have low resistance Material of wire – aluminum and copper have low resistance Thickness – the thicker the wire the lower the resistance Thickness – the thicker the wire the lower the resistance Length – shorter wire has lower resistance Length – shorter wire has lower resistance Temperature – lower temperature has lower resistance Temperature – lower temperature has lower resistance

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What is Voltage? The measure of energy given to the charge flowing in a circuit. The measure of energy given to the charge flowing in a circuit. Voltage is the “push” that makes electric charges move. Voltage is the “push” that makes electric charges move. The greater the voltage, the greater the force or “pressure” that drives the charge through the circuit. The greater the voltage, the greater the force or “pressure” that drives the charge through the circuit.

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Difference b/t Volts and Amps Example – you could say that… Example – you could say that… Amps measure how much water comes out of a hose. Amps measure how much water comes out of a hose. Volts measure how hard the water comes out of a hose. Volts measure how hard the water comes out of a hose.

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How can we control current? With circuits. With circuits. Circuit: is a path for the flow of electrons. We use wires. Circuit: is a path for the flow of electrons. We use wires.

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There are 2 types of circuits: Series Circuit: the components are lined up along one path. If the circuit is broken, all components turn off. Series Circuit: the components are lined up along one path. If the circuit is broken, all components turn off.

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Series Circuit

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Current is the same throughout the circuit. Current is the same throughout the circuit. The voltage drops after each load. The voltage drops after each load. Total Resistance = R 1 + R 2 +… Total Resistance = R 1 + R 2 +…

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There are 2 types of circuits: Parallel Circuit – there are several branching paths to the components. If the circuit is broken at any one branch, only the components on that branch will turn off. Parallel Circuit – there are several branching paths to the components. If the circuit is broken at any one branch, only the components on that branch will turn off.

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Parallel Circuit

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The voltage is the same everywhere in the circuit. The voltage is the same everywhere in the circuit. The current is less in each branch of the circuit. Add them together for the total current. The current is less in each branch of the circuit. Add them together for the total current. 1 = 1 + 1 + … 1 = 1 + 1 + … Total resistance R1 R2 Total resistance R1 R2

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Ohm’s Law Resistance = Voltage / Current Resistance = Voltage / Current Ohms = Volts / Amps Ohms = Volts / Amps

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Practice with Ohm’s Law OhmsVoltsAmps 410025 1515010 23015 9455 6488

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What is electric power? Electric power is the rate at which electricity is converted into another form of energy. Electric power is the rate at which electricity is converted into another form of energy. Power = current x voltage Power = current x voltage The unit of electrical power is the watt or kilowatt The unit of electrical power is the watt or kilowatt

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What is electric energy? Electrical energy is power x time Electrical energy is power x time The unit is the kilowatt-hour The unit is the kilowatt-hour

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What is an electromagnet? Electromagnet – a magnet made from a current bearing coil of wire wrapped around an iron or steel core. Electromagnet – a magnet made from a current bearing coil of wire wrapped around an iron or steel core.

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What is a generator? Generator – a machine that changes mechanical energy to electrical energy Generator – a machine that changes mechanical energy to electrical energy Usually use moving magnets to create currents in coils of wire. Usually use moving magnets to create currents in coils of wire.

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What is a motor? Motor – a device that changes electrical energy to mechanical energy that can do work. Motor – a device that changes electrical energy to mechanical energy that can do work.

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That’s It !!!!

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Electricity and magnetism

Electricity and magnetism

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