Electricity & Magnetism

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Electricity & Magnetism. Static, Currents, Circuits Magnetic Fields & Electro Magnets Motors & Generators. Atoms…. Have neutrons , protons , and electrons . Protons are positively charged Electrons are negatively charged. An Atom. Electrons…. - PowerPoint PPT Presentation

Text of Electricity & Magnetism

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

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

  • An Atom

  • 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.

  • Atoms with an excess of electrons are called negative ions and those that are missing electrons in the shells or orbits are called positive ions.

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


  • ElectricityElectricity is the movement of free electrons in a material toward an area of positive (+) charges.The conduction of those electrons is determined by the type of material.

  • A buildup of opposite charges creates an electric potential. Release of the potential energy results in the movement of free electrons, which is called electricity.

  • Types of ElectricityStatic electricityCurrent electricityDirect currentAlternating current

  • 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 contactNonconduction (Insulators) through an electrical field (not direct contact)

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

  • 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

  • CircuitsElectric CircuitsDevices rely on a source of electrical energy and wires to complete an electric circuits.Circuits typically include:A voltage sourceA conductor (such as a wire)A device that uses the electrical energy to do work.

  • 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

  • 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

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

    Insulators materials through which electric current cannot move.

  • ConductorsSolid metals are good conductors of electricity, because electrons are allowed to move freely throughout the material. Copper and gold are some of the best conductors of electricity.

  • Insulators (Nonconductors)Nonconductors inhibit the movement of electrons within the material. But they often do allow electrons and ions to collect on their surfaces. Examples of nonconductors or electrical insulators are: Plastic Rubber Glass Most metal oxides (like rust) Air Oil Pure, de-ionized water

  • 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 Current can be measured with an instrument called an AMMETER. The AMMETER determines how much charge passes through it every Second. THIS MOVEMENT, OR CURRENT, IS MEASURED IN SI UNITS CALLED AMPERES (A).

  • What is Voltage?The measure of energy given to the charge flowing in a circuit.The SI unit is volts with the symbol (V)The greater the voltage, the greater the force or pressure that drives the charge through 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 / Ampswhere I is the current in amperes, V is the potential difference between two points of interest in volts, and R is a constant, measured in ohms, called the resistance. V = I x R

  • Practice with Ohms Law


  • 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 !!!!