Chapter 8 Ohm’s law describes the relationship of current, voltage and resistance Pages 248-283 1

Chapter 8 Ohm’s law describes the relationship of current, voltage and

resistance

Pages 248-283

1

8-1 Electric Potential Energy and Voltage

Pages 250-259

2

3.06.1 Use an ammeter and a voltmeter to measure current and voltage in a circuitAmmeter• A device used to

measure current.

Voltmeter• A device used to measure

the potential difference

3

3.06.2 Identify the volt (V) as the SI unit for electric potential• Unit used to

measure electric potential energy is the volt (V).

• Named after Alessandro Volta

• Measured by using a device called voltmeter 4

3.06.1 Define electric potential differenceThe amount of electric potential energy

per one coulomb of chargeThe change in potential energy per

coulomb of chargeMeasured in volts (V)Also known as voltage

5

Section 8.2 Electric Current

Pages 260-269

6

3.07 Describe the flow of charge in an electric circuit

7

3.07.1 Define electric circuit

• A complete pathway that allows electrons to flow

8

3.07.2 Identify that electric potential is provided as the source and is “used” by the circuit elements

9

3.07.3 Describe the parts of an electric circuit.I. Source of electrical

energy

II. Electrical load

III. Controls/switch

IV. Conductor

10

3.08 Explain the importance of using precise language while studying the characteristics of

electricity

11

3.08.1 Define electric current

Electric Current The amount of charge passing a given

point in a conductor per second. Measured in amperes (A) Measured using

1. ammeter…strong current2. galvanometer…weak current

12

3.08.2 Identify the ampere (A) as the SI unit for currentUnit used to measure current … ampereMeasured using

Ammeter…strong currentGalvanometer…weak current

Name after Andre Marie AmpereNamed after Luigi Galvani

Ampere 13

3.09 Compare static electricity and current electricityCurrent ElectricityThe continuous flow

of charge in a complete circuit.

Static ElectrictyBuild-up of electric

charges in an object.Jumps from one

object to another

14

3.10 Organize information using a format appropriate to studying and describing current electricity

• Circuit Diagrams• See symbols on page 262.

15

3.10.1 Create circuit diagrams using appropriate circuit symbolsI. BulbII. CellIII. BatteryIV. WiresV. ResistorsVI. AmmeterVII.VoltmeterVIII.Open switchIX. Closed switch 16

3.10.1 continued…

• Draw and interpret electric circuit diagrams using electric symbols

• Activity - Page 263

17

8.3 Resistance and Ohm’s Law

Pages 270-283

18

3.10.2 Define electrical resistance

Electrical ResistanceSlows down the flow of

electrons. (resistors)Transforms electrical

energy into light, heat, etc.

The ratio of the voltage to the current.

R = V I 19

3.10.3 Identify the ohm (Ω) as the SI unit for electrical resistance• Electrical resistance

is measured in ohm’s (Ω)• Measured using

ohmmeter• Named after

George Simon Ohm20

3.10.4 List factors which affect the amount of resistance in a wireI. LengthII. DiameterIII. TypeIV. Temperature

21

Ohm’s Law…animation

• http://www.physicslessons.com/phe/ohmslaw.htm

• http://www.physicslessons.com/exp41.htm

22

3.11 State a prediction and a hypothesis based on background information or an observed pattern of events

• Activity 8-3 B pages 275

23

3.12 Identify new questions and problems that arise from what was learned concerning voltage, current, and resistance

• Activity 8-3 B pages 275

24

3.12.1 State Ohm’s Law

Ohm’s LawThe mathematical relationship between voltage (V), current (I) and resistance (R)

25

3.12.2 Given voltage drop and current through a resistor, calculate its resistance

Complete the practice problems Pages 273-275

26

3.12.3 Given voltage drop and resistance, calculate current through a resistor

Complete the practice problemsPages 273-275

27

3.12.4 Given current through a resistor and its resistance, calculate the voltage drop

Complete the practice problems Pages 273-275

28

Video…Ohms Law

• http://www.youtube.com/watch?v=JRp_iSaVRjE&feature=related

• http://www.youtube.com/watch?v=_-jX3dezzMg

• http://www.youtube.com/watch?v=8utldTdAJmk&feature=related

29

3.13 Identify potential sources of error in ammeter and voltmeter readings

Activity 8-3D Pages 278-279

30

3.14 Identify and suggest explanations for discrepancies in data collected using an ammeter and voltmeter

• Activity 8-3D Pages 278-279

31

3.15 Present graphically, using the line of best fit, data from investigation of voltage, current, and resistance

• Activity 8-3D Pages 278-279

32