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Unit 10 Chapter 13

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Page 1: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Unit 10

Chapter 13

Page 2: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Consumer warning:You will have carpal tunnel syndrome by the

end of this unit if you don’t learn how to summarize the information contained in this powerpoint.

Page 3: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Think of all the ways electricity can be found in

your daily life.

Could you survive without electricity?

Page 4: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Electric charge and force

Page 5: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Electric charge is an electrical property of matter that creates a force between objects.

All matter is made of atomsAtoms are composed from 3 essential particles

Neutrons – in the nucleus with a neutral charge

Proton – in the nucleus with a (+) chargeElectron – outside the nucleus with a (-)

charge

Page 6: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Electric charge cont. SI unit of electric charge is the coulomb, CElectrons and protons have exactly the

same amount of charge… 1.6 x 10-19 CBecause they are oppositely charged.

Protons is a +1.6 x 10-19 CElectrons is a -1.6 x 10-19 C

If an object has excess electrons then it has an electric charge. The net electric charge is always a

multiple of 1.6 x 10-19 C.

Page 7: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Atoms become charged by gaining or losing electrons

Static electricity is the accumulation of excess electric charges on an object

Page 8: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

What are the rules?

Law of Conservation of Charge

Charge may be transferred from object to object but it

cannot be created or destroyed

Page 9: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

More rulesOpposites attract and like charges repel

Charges can act at great distances

Any charge placed in an electric field will be pushed or pulled by the field

Page 10: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this
Page 11: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Still more rulesElectrons move more easily through conductors like metals

Electrons do no move easily through insulators such as plastic, wood, rubber, and glass

Page 12: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this
Page 13: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this
Page 14: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Really dry air

Page 15: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

With a big enough build up of charge, electricity WILL flow

Page 16: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this
Page 17: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this
Page 18: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Like say half a megavolt trying to pass through a wire

Page 19: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this
Page 20: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Conductors and InsulatorsA conductor is a material that transfers

charge easilyIt allows the charges to flowExample: metal

An insulator is a material that does not transfer charge easilyIt will not allow the charges to flowExamples: cardboard, glass, silk, and

plastic

Page 21: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Transferring a ChargeThree main methods

Charging by contactCharging by InductionStatic Discharge

Page 22: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Charging by contactDone by touching or rubbingExample: feet rubbing the carpet then touching a metal door knob

Page 23: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Charging by InductionElectrons move because of a nearby charged object

Example: negatively charged balloon near your sleeve causes your sleeve to be positively charged

Page 24: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Static DischargeA transfer of charge through the air between two objects because of the buildup of a static electricity – a spark!

Example: lightning

Page 25: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Last bitsGrounding – using a conductor to direct the charge into the groundIt an important part of electrical safety!

The presence of a charge can be determined by an electroscope

Page 26: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this
Page 27: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Electric forceElectric force is the force of attraction or repulsion between objects due to chargeIt is the reason why some clothes cling

together when you take them out of the dryer

It is part of what holds an atom togetherIt also plays a part in chemical bonding

Without electric force, life itself would be impossible

Page 28: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Electric force cont.The electric force between 2 charged

objects varies depending on the amount of charge on each object and the distance between them

Acts through a fieldElectric field is the region around a

charged object in which other charged objects experience an electric force

Page 29: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Electric force cont.Regardless of the charge, electric field

lines never cross one another

Page 30: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Current

Page 31: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Electrical potential energyElectrical potential energy is the potential energy of a charged object due to its position in an electric field

Potential difference is the change in the electrical potential energy per unit chargeSI unit for potential difference is the volt

(V) which is equivalent to 1 joule per coulomb

Often called voltage

Page 32: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Electric current The flow of charges through a wire or conductor is called electric current

Current is the rate that electric charges move through a conductor

SI unit of current is Amperes (A or amp)

Page 33: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

VoltageCharges flow from high voltage to low voltage

A voltage difference is the push that causes charges to move

Voltage difference is measured in volts (V)

For charges to flow, the wire must always be connected in a closed path or circuit

Page 34: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Sources of electricityCell is a device that is a source of electric current because of a potential difference, or voltage between the terminals

Dry cell – standard battery – produces a voltage difference by a chemical reaction

Wet cell – car battery – produces a voltage difference by chemical reaction

Wall sockets – AC – produced at a generator

Page 35: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Types of electric cellsElectrochemical – Electrons transferred

between different metals immersed in an electrolyteUses – common batteries and automobile

batteries

Photoelectric and photovoltaic – Electrons are released from a metal when struck by light of sufficient energyUses –satellites, calculators, and

streetlights

Page 36: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Types of electric cellsThermoelectric – Two different metals are

joined together, and the junctions are held at different temperatures, causing electrons to flow.Uses – Thermostats for furnaces and ovens

Piezoelectric – Opposite surfaces of certain crystals become electrically charged when under pressure.Uses – crystal microphones and headsets,

computer keypads

Page 37: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this
Page 38: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this
Page 39: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Conventional current was the original idea……

Conventional current is the movement of positive charge

It is current made of positive charge that would have the same effect as the actual motion of charge in the material

Page 40: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Electrical ResistanceResistance is the ratio of the voltage across a conductor to the current it carries

The tendency for a material to oppose the flow of electrons, changing electrical energy into thermal energy and light

All materials have some resistance

Page 41: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Still resistingSI unit of resistance is ohms (Ω)It is equal to volts per ampere

Resistor is a special type of conductor used to control current

Making wires thinner, longer, or hotter increases resistance

Page 42: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Light bulbslight bulbs make use of resistance

Page 43: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this
Page 44: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this
Page 45: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Ohm’s Law

I = V R

I – current (A)V – voltage (V)R – resistance (Ω)

Page 46: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Practice problemWhat is the resistance of a wire that has

a current of 1.4 A in it when it is connected to a 6.0 V battery?

R = V I

Page 47: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Practice problemWhat is the resistance of a wire that has

a current of 1.4 A in it when it is connected to a 6.0 V battery?

R = V I = 6.0 V = 4.3 Ω 1.4 A

Page 48: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Practice problemAn electric space heater is plugged into a

120 V outlet. A current of 12.0 A is in the coils in the space heater. What is the resistance of the coils?

Page 49: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Practice problemAn electric space heater is plugged into a

120 V outlet. A current of 12.0 A is in the coils in the space heater. What is the resistance of the coils?

R = V I = 120 V = 10 Ω 12.0 A

Page 50: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Practice problemA steam ion has a current of 9.17 A when

plugged into a 120 V outlet. What is the resistance of the steam iron?

Page 51: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Practice problemA steam ion has a current of 9.17 A when

plugged into a 120 V outlet. What is the resistance of the steam iron?

R = V I = 120 V = 13 Ω 9.17 A

Page 52: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Practice problems……………………..

Page 53: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

1

120.12V

Page 54: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

2

4.8V

Page 55: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

3

116.5V

Page 56: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

4

119.56V

Page 57: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

5

4.55V

1.5V per battery

Page 58: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

6

2.9A

Page 59: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

7

15A

Page 60: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

8

4.79A

Page 61: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

9

5.2A

Page 62: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

10

230.77Ω

Page 63: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

11

179.2 Ω

Page 64: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Anybody do #14?

5.74A

Page 65: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

More on resistance….Conductors have low resistancesThey allow the electrons to flow easily and therefore have a low resistance

Page 66: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Still resistingSome materials become superconductors below a certain temperatureCertain metals and compounds have

zero resistance when their temperature falls below the critical temperature

The critical temperature varies between -272oC and -123oC

Examples – tin, mercury, and some metallic compounds containing barium, copper, and oxygen

Page 67: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Still resistingInsulators have high resistance to charge movementThey are used to prevent electric

current from leakingExamples - plastic coating around

copper wire of an electric cord keeps the current from escaping into the floor or your body

Page 68: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Circuits

Page 69: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

What are circuits?Electric circuit is an electrical device connected so that it provides one or more complete paths for the movement of chargesClosed circuit is one in which there is

a closed-loop path for electrons to follow

Open circuit is one without a complete path, there is no charge flow and therefore no current

Page 70: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

CircuitsSchematic diagram is a graphic representation of an electric circuit or apparatus, with standard symbols for the electrical devices

Page 71: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Electrical CircuitsCircuits rely on generators at power plants to produce a voltage difference across the outlet, causing the charge to move when the circuit is complete

Page 72: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Series and Parallel circuitsSeries describes a circuit or portion of a circuit that provides a single conducting path

Parallel describes components in a circuit that are connected across common points, providing two or more separate conducting paths

Page 73: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Series circuitThe current has only one loop to flow through

The parts of the series circuit are wired one after another so the amount of current is the same through every part

Page 74: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this
Page 75: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this
Page 76: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this
Page 77: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Series circuits cont. Open circuit – If any part of a series circuit is disconnected, no current flows through the circuitExample – Christmas lights

Page 78: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Parallel CircuitsContain two or more branches for current to move through

Individual parts can be turned off without affecting the entire circuitExample – circuits in a house

Page 79: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this
Page 80: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this
Page 81: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Electric Power and Electrical EnergyElectrical energy is the energy associated with electrical charges, whether moving or at restThe energy may come from a

battery or a power plantElectric Power

Power = current x voltageP = IV

SI unit for power is the watt (W)

Page 82: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Practice problemA flashlight has a potential difference of 3.0 V. The bulb has a current of 0.50 A. What is the electric power used by the flashlight?

P = IV = 3.0 V x 0.50 A = 1.5 W

Page 83: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Practice problemWhat is the current in a 60 W light bulb when it plugged into a 120 V outlet?

Page 84: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Practice problemWhat is the current in a 60 W light bulb when it plugged into a 120 V outlet?

I = P V = 60 W = 0.5 A 120 V

Page 85: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

Household circuitsUse parallel circuits Each branch receives the standard voltage difference

Electricity enters your home at the circuit breaker or fuse box and branches out to the rest of your house

Page 86: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this

House guardsElectric fuse – contains a small piece of metal that melts if current becomes too high and breaks the circuit

Circuit breaker – uses a magnet or bimetallic strip (a strip with two different metals welded together) that responds to current overload by opening the circuit.It protects a circuit from current

overloadsUsed in many homes and businesses

Page 87: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this
Page 88: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this
Page 89: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this
Page 90: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this
Page 91: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this
Page 92: Unit 10 Chapter 13. You will have carpal tunnel syndrome by the end of this unit if you don’t learn how to summarize the information contained in this