Electricity & Magnetism Static, Currents, & Electro Magnets Motors & Generators

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Text of Electricity & Magnetism Static, Currents, & Electro Magnets Motors & Generators

  • Electricity & MagnetismStatic, Currents, & Electro MagnetsMotors & Generators

  • AtomsHave neutrons, protons, and electrons.Protons are positively chargedElectrons are negatively charged

  • ElectronsAre located on the outer edges of atomsthey can be moved.A concentration of electrons in an atom creates a net negative charge.If electrons are stripped away, the atom becomes positively charged.

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

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

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

  • Static DischargeOccurs when there is a loss of static electricity due to three possible things:Friction - rubbingConduction direct contactInduction through an electrical field (not direct contact)

  • Lightning

    Large static discharge between the earth and clouds.Lightning was found to be static electricity by Ben Franklin.GroundingConductive path to Earth.Lightning rods & plumbing.

  • The electroscope can be used to detect electric charge

  • Electricity that movesCurrent: The flow of electrons from one place to another.Measured in amperes (amps)Kinetic energyThe amount of electric charge is measured in coulombs.1 coulomb is the charge carried by 6.24 x 10^18 e.1 amp (A) is 1 coulomb per sec (C/s)

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

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

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

  • Conductors vs. InsulatorsConductors material through which electric current flows easily.

    Insulators materials through which electric current cannot move.

  • ExamplesConductors:MetalWaterInsulators:StyrofoamRubberPlasticPaper

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

  • What Influences Resistance?Material of wire aluminum and copper have low resistanceThickness the thicker the wire the lower the resistanceLength shorter wire has lower resistanceTemperature lower temperature has lower resistance

  • Electric CurrentThe reason electric charge flows from one place to another is voltage.

    Voltage is the difference in electrical potential between two places where e are flowing.Voltage is the push that makes electric charges move.Measured in volts (V).

    HIGHLOW

  • BatteriesBatteries are e pumps.They provide a voltage difference to a circuit.Types: wet-cells & dry-cells

  • Kirchoffs LawsKirchoffs First Law states that current entering a junction is equal to the current leaving the junction.

    Kirchoffs Second Law states that the sum of the voltage drops around a complete circuit loop or path is equal to the applied voltage to the circuit.

  • Difference b/t Volts and AmpsExample you could say thatAmps measure how much water comes out of a hose.Volts measure how hard the water comes out of a hose.

  • Ohms Law

    Resistance = Voltage / Current

    Ohms = Volts / Amps

    Where: Current = I Voltage = V Resistance = R

  • Practice with Ohms Law

    OhmsVoltsAmps41002515150102301594556488

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

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

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

  • Thats It !!!!

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