electric charge and static electricity

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Electric Charge and Static Electricity. Ch 20.1. Electric Charge. Property that causes subatomic particles (_____, ______) to attract/repel each other 2 Types Positive- Protons Negative- Electrons. Net Electric Charge Excess or shortage of electrons SI Unit Coulomb (C) - PowerPoint PPT Presentation


Electric Charge and Static Electricity

Ch 20.1Electric Charge and Static Electricity1TrueFalseStatementTrueFalseLike charges attract, opposite charges repelElectric charge is due to an excess or shortage of electronsLaw of Conservation of Charge says that charge is constantYou can charge an object by touching, friction and inductionThe SI unit for static electricity is the coulomb 2Electric ChargeProperty that causes subatomic particles (_____, ______) to attract/repel each other

2 TypesPositive- ProtonsNegative- Electrons

Net Electric ChargeExcess or shortage of electronsSI UnitCoulomb (C)6.24 x 1018 electrons

3Electric ForcesLike charges RepelOpposite chargesAttractElectric ForceForces of attraction and repulsion between electrically charged objectsCharles CoulombDiscovered electric forces are similar to the law of Gravitation

4Electric FieldsThe strength of an electric field depends onThe amount of charge that produces the fieldThe distance from the chargeThe force depends onThe net charge in the objectThe strength and direction of the fields position

5Static Electricity and ChargingThe study of the behavior of electric charges and how charge is transferred

Law of Conservation of ChargeTotal charge in an isolated system is constant1. Charging by FrictionEx. Rubbing a Balloon in your hairElectrons move due to attraction

6Static Electricity and Charging2. Charging by ContactEx. Van de Graaff generator3. Charging by InductionEx. Reaching for a doorknob after rubbing feet across carpet

Induction- transfer of charge without contact between materials

7Static DischargeOccurs when a pathway through which charges can move forms suddenly

8Ch 20.2Electric Current and Ohms Law9TrueFalseStatementTrueFalseDC current is current in all direction, while AC current reversesThickness, length and temperature affect resistanceOhms Law says resistance(R), voltage(V) and current(I) are co-relatedPotential difference is also voltage, or the difference between 2 places in an electric fieldConductors help current to flow easily while insulators prevent current from flowing10Electric CurrentContinuous path through which charge can flowSI UnitAmpere/Amp (A)1 C/s

2 Types of Current1. Direct Current (DC)Charge flows in 1 directionFlashlights, battery operated machines

2. Alternating Current (AC)Charge flow reverses directionElectricity in buildings11

12Electric ConductorElectric InsulatorMaterial electric charge can flow easily throughCu, AgMaterial electric charge cannot flow easily throughWood, plastic, rubber, airConductors and Insulators13ResistanceOpposition to the flow of charges in a materialSI UnitOhm

SuperconductorMaterial that has almost zero resistance when it is cooled to a low temperature3 Factors Affecting ResistanceThicknessLengthTemperature

14VoltageIn order for a charge to flow in a conducting wire, the wire must be connected in a complete loop that includes a source of electric energy15Potential DifferenceVoltage SourcesCharges flow from higher to lower potential energyPD- difference in electrical PE between 2 places in an electric fieldSI UnitJ/C or VoltsAlso called voltage

BatteryDevice that converts chemical energy to electrical energySolar cells, generatorsVoltage16Ohms LawVoltage(V) in a circuit equals the product of the current(I) and the resistance(R)

Increasing the voltage increases currentKeeping the same voltage and increasing resistance decreases the currentV = I x R

Ex. 3 amps x 3 ohms= 9volts

17Ch 20.3Electric Circuits18TrueFalseStatementTrueFalseCircuit diagrams use symbols to represent an electrical circuitA closed circuit stops, while an open circuit is free to flowSeries circuits only have one way to flowParallel circuits have 2 or more paths in which to flowA fuse prevents current overload, and melts in over use19Circuit DiagramsElectric CircuitComplete path through which charge can flow

Circuit Diagrams Use symbols to represent parts of a circuit, electrical energy and devices run by electrical energyOpen CircuitOpen switch = current stops

Closed CircuitClosed switch = complete flow of current

20Series CircuitCharge has only 1 path through which it can flowIf 1 element stops working, none of the elements can operate

21Parallel CircuitElectric circuit with 2 or more paths through which charges can flowIf 1 element stops functioning the rest can still operate

22Power and Energy Calculations Electrical PowerRate at which electrical energy is converted to another form of energySI UnitJ/s or Watt (W)Kilowatt (kW)

P(watts)= I(amps) x V(volts)Electrical EnergySI Unit W skW hr

E= P x t23Math Practice pg 6111.

3. 2.24Electrical SafetyElectrical Energy SafetyCorrect wiringFusesCircuit BreakersInsulationGrounded Plugs

25Home SafetyPersonal SafetyFusePrevents current overloadBlowing a fuse- melting a fuseCircuit BreakerSwitch the opens when a current in a circuit is too highGroundingTransfer of excess charge through a conductor to EarthElectrical Safety

26Ch 20.4Electronic Devices27TrueFalseStatementTrueFalseAnalog signals change voltage, while digital signals change current.Vacuums are the best way to control electronic signals, compared to solid state componentsA diode has a n-type and p-type semiconductorA n-type semiconductor flows protons, while a p-type semiconductor flows electronsAn integrated circuit replaces many vacuums and is also called a microchip28Electronic SignalsElectronicsThe science of using electronic current to process/transmit informationElectronic SignalInformation sent as patterns in the controlled flow of electrons through a circuit

29Analog SignalDigital SignalsSmoothly varying signal produced by continually changing the voltage or current

AM radioEncodes information as a string of 1s and 0s

DVDsElectronic Signals

30Vacuum TubesChange alternating current into direct currentIncrease the strength of a signalTurn a current on or off

Cathode Ray TubeUsed in computer monitors, TVsPhosphors glow red, green or blue

31SemiconductorsCrystalline solid that conducts current only under certain conditions

N Type SemiconductorCurrent is a flow of electronsMade by adding P to SiP Type SemiconductorAppears as though positive charge flowsMade by adding B to Si

32Solid State ComponentsUsed solids instead of vacuums to control current1. DiodesSolid state component that combines N Type and P Type semiconductors

Flows from N to PCan change alternating current to direct

33Solid State Components2. TransistorsSolid state component with 3 layers of semiconductors

Used as a switch or amplifier3. Integrated CircuitsThin slice of Si containing many solid state componentsChips or microchipsPerform as well as a network of vacuums

34Communications TechnologyComputerProgrammable device that stores and processes information

Communication devices use microchips to make themPortableReliableaffordable



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