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

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

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Electricity & MagnetismElectricity & Magnetism

Static, Currents, CircuitsStatic, Currents, Circuits

Magnetic Fields & Electro MagnetsMagnetic Fields & Electro Magnets

Motors & GeneratorsMotors & Generators

Atoms…Atoms…

Have Have neutronsneutrons, , protonsprotons, and , and electronselectrons..

Protons are Protons are positivelypositively charged chargedElectrons are Electrons are negativelynegatively charged charged

An AtomAn Atom

Electrons…Electrons…

Are located on the Are located on the outerouter edges of edges of atoms…they can be atoms…they can be movedmoved..

A A concentrationconcentration of electrons in an of electrons in an atom creates a net atom creates a net negativenegative charge.charge.

If electrons are If electrons are strippedstripped away, the away, the atom becomes atom becomes positivelypositively charged. charged.

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

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The world is filled with The world is filled with electrical electrical chargescharges::

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THE LAW OF THE LAW OF CONSERVATION OF CONSERVATION OF

CHARGECHARGE THE LAW OF CONSERVATION OF THE LAW OF CONSERVATION OF

CHARGE STATES THAT AN ELECTRIC CHARGE STATES THAT AN ELECTRIC CHARGE CANNOT BE CREATED OR CHARGE CANNOT BE CREATED OR DESTROYED. DESTROYED.

ElectricityElectricity

Electricity is the movement of free Electricity is the movement of free electrons in a material toward an area of electrons in a material toward an area of positive (+) charges.positive (+) charges.

The conduction of those electrons is The conduction of those electrons is determined by the type of material. determined by the type of material.

A buildup of opposite charges creates an A buildup of opposite charges creates an electric potentialelectric potential. .

Release of the potential energy results in Release of the potential energy results in the movement of free electrons, which is the movement of free electrons, which is called electricity.called electricity.

Types of ElectricityTypes of Electricity

Static electricityStatic electricityCurrent electricityCurrent electricity

Direct currentDirect currentAlternating currentAlternating current

What is this electrical What is this electrical potentialpotential called?called?

Static ElectricityStatic Electricity

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Static ElectricityStatic Electricity

The The build upbuild up of an electric charge of an electric charge on the on the surfacesurface of an object. of an object.

The charge builds up but The charge builds up but does does not flow.not flow.

Static electricity is Static electricity is potential potential energyenergy. It does . It does notnot move. It is move. It is storedstored..

Static Discharge…Static Discharge…

Occurs when there is a Occurs when there is a lossloss of static of static electricity due to three possible electricity due to three possible things:things:

FrictionFriction - rubbing - rubbingConductionConduction – direct contact – direct contactNonconduction (Insulators)Nonconduction (Insulators) – – through an electrical field (not direct through an electrical field (not direct contact)contact)

Electricity that Electricity that movesmoves……

CurrentCurrent: The flow of electrons : The flow of electrons from one place to another.from one place to another.

Measured in Measured in amperesamperes (amps) (amps)KineticKinetic energy energy

How can we How can we controlcontrol currents? currents?

With With circuitscircuits..CircuitCircuit: is a : is a pathpath for the flow of for the flow of

electrons. We use electrons. We use wireswires..

There are 2 types of currents:There are 2 types of currents:

Direct Current (DC)Direct Current (DC) – Where – Where electrons flow in the electrons flow in the samesame direction in a wire. direction in a wire.

There are 2 types of currents:There are 2 types of currents:

Alternating Current (AC)Alternating Current (AC) – – electrons flow in electrons flow in differentdifferent directions in a wiredirections in a wire

CircuitsCircuits

Electric CircuitsElectric CircuitsDevices rely on a source of electrical energy Devices rely on a source of electrical energy

and wires to complete an electric circuits.and wires to complete an electric circuits.Circuits typically include:Circuits typically include:

A voltage sourceA voltage sourceA conductor (such as a wire)A conductor (such as a wire)A device that uses the electrical energy to do work.A device that uses the electrical energy to do work.

There are 2 types of circuits:There are 2 types of circuits:

Series CircuitSeries Circuit: the components : the components are lined up along are lined up along oneone path. If path. If the circuit is broken, the circuit is broken, all all components turn off.components turn off.

Series CircuitSeries Circuit

There are 2 types of circuits:There are 2 types of circuits:

Parallel CircuitParallel Circuit – there are – there are severalseveral branching paths to the branching paths to the components. If the circuit is components. If the circuit is broken at any one branch, broken at any one branch, only only the components on that branch the components on that branch will turn offwill turn off..

Parallel CircuitParallel Circuit

Conductors vs. InsulatorsConductors vs. Insulators

ConductorsConductors – material through – material through which electric current flows which electric current flows easilyeasily..

InsulatorsInsulators – materials through – materials through which electric current which electric current cannot cannot movemove..

ConductorsConductors

Solid metals are good Solid metals are good conductorsconductors of of electricityelectricity, because , because electrons are allowed electrons are allowed to move freely throughout the materialto move freely throughout the material. .

Copper and gold are some of the best Copper and gold are some of the best conductors of electricity.conductors of electricity.

Insulators (Nonconductors)Insulators (Nonconductors)

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

What is Resistance?What is Resistance?

The The oppositionopposition to the flow of an to the flow of an electric current, producing electric current, producing heatheat..

The The greatergreater the resistance, the the resistance, the lessless current gets through. current gets through.

GoodGood conductors have conductors have lowlow resistance.resistance.

Measured in Measured in ohms.ohms.

What Influences Resistance?What Influences Resistance?

Material of wireMaterial of wire – aluminum and – aluminum and copper have low resistancecopper have low resistance

ThicknessThickness – the thicker the wire the – the thicker the wire the lower the resistancelower the resistance

LengthLength – shorter wire has lower – shorter wire has lower resistanceresistance

TemperatureTemperature – lower temperature has – lower temperature has lower resistancelower resistance

Electric Current can be measured with an Electric Current can be measured with an instrument called an AMMETER.  The instrument called an AMMETER.  The AMMETER determines how much charge AMMETER determines how much charge passes through it every Second. passes through it every Second.

THIS MOVEMENT, OR CURRENT, IS THIS MOVEMENT, OR CURRENT, IS MEASURED IN SI UNITS CALLED MEASURED IN SI UNITS CALLED AMPERES (A). AMPERES (A).

What is Voltage?What is Voltage?

The The measure of energymeasure of energy given to the given to the charge flowing in a circuit.charge flowing in a circuit.

The SI unit is volts with the symbol The SI unit is volts with the symbol (V)(V)

The The greatergreater the voltage, the the voltage, the greater greater the force or “pressure”the force or “pressure” that drives that drives the charge through the circuit.the charge through the circuit.

Difference b/t Volts and AmpsDifference b/t Volts and Amps

Example – you could say that…Example – you could say that…AmpsAmps measure measure how muchhow much water water

comes out of a hose.comes out of a hose.VoltsVolts measure measure how hardhow hard the water the water

comes out of a hose.comes out of a hose.

Ohm’s LawOhm’s Law

Resistance = Voltage / CurrentResistance = Voltage / Current

Ohms = Volts / AmpsOhms = Volts / Amps

where 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 Ohm’s LawPractice with Ohm’s Law

OhmsOhms VoltsVolts AmpsAmps

44 100100 2525

1515 150150 1010

22 3030 1515

99 4545 55

66 4848 88

What is an electromagnet?What is an electromagnet?

ElectromagnetElectromagnet – a magnet made – a magnet made from a from a current bearing coilcurrent bearing coil of wire of wire wrapped around an wrapped around an iron or steel iron or steel core.core.

What is a generator?What is a generator?

GeneratorGenerator – a machine that – a machine that changes changes mechanicalmechanical energy to energy to electricalelectrical energy energy

Usually use Usually use movingmoving magnets to magnets to create create currentscurrents in coils of wire. in coils of wire.

What is a motor?What is a motor?

MotorMotor – a device that changes – a device that changes electrical electrical energy to energy to mechanical mechanical energy that can do energy that can do workwork..

That’s It !!!!That’s It !!!!