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

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.

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

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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 of static electricity due to three static electricity due to three possible things:possible things:

FrictionFriction - rubbing - rubbingConductionConduction – direct contact – direct contactInductionInduction – through an electrical – through an electrical field (not direct contact)field (not direct 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

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..

ExamplesExamples

ConductorsConductors::MetalMetalWaterWater

InsulatorsInsulators::StyrofoamStyrofoamRubberRubberPlasticPlasticPaperPaper

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

What is Voltage?What is Voltage?

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

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

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 !!!!