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G r ade

G r ade. 9. Science. Unit. 3:. Electri c ity. Chapter. 9 : Circuits a r e. designed to control the transfer of electrical energy. Seri e s Circuits • There is only one path for the current to travel. • bulbs connected in series; when one goes out, they all go out.

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  1. Grade 9 Science Unit 3: Electricity Chapter 9:Circuits are designed to control the transfer ofelectricalenergy.

  2. SeriesCircuits •There isonly onepath for the current totravel. •bulbs connected inseries; when onegoes out,they all go out.

  3. •As you addmorebulbs, brightness ofthe bulbs decreases. (voltageis affected) •Addingmorebulbs increases theresistance the thereby decreasingthetotal current inthecircuit.

  4. Ex.Christmaslights

  5. Parallel Circuits •Acircuit withseveral differentpaths. •Bulbs connected in parallel; when onegoes out,the others are unaffected.

  6. •As you addmorebulbs, the brightness isunaffected. (voltageis unaffected) •Resistance doesnot increase. •No current is createdor destroyed onlysplit up.

  7. •Addingresistorsinparallel will decreasethe total resistance. Thiswill increase thetotalcurrent leavingthe battery.

  8. SeriesCircuit ParallelCircuit #ofPathways Effectofremoving aload Voltagedrop Current Resistance Connectingcellsto formabattery

  9. Core LabActivity Resistors in Series and Parallel pg. 300-1

  10. Series vs. Parallel Circuits Series Parallel Lighthouse: lifespan Flashlight: V = I = = maintenance

  11. Technologies for Safe Use of Electricity

  12. •Circuit Breakers Act as a switchthatcan cut off all power coming intoyour house.

  13. •Fuses Contains a metallic conductorthat meltswhen excessive current heats it up.

  14. •Groundingterminals Allows excesscurrent to flow in to theground insteadof givingyou a shock.

  15. Electrical Energy •The abilityto do work •Measured inJoules (J)

  16. ElectricalPower •The rate of changein electrical energy •The rate at which done orenergyis transformed. work is •Measured inWatts(W)

  17. Electrical Energy Costs Depend on3factors: 1. 2. 3. Voltage drop Electrical current Time

  18. Power Rating •Ameasurementof how much electricalenergy an electrical deviceconsumes foreverysecond it isinuse.

  19. Calculating Energy Consumption (J) E=energytransferred P=power(W) t=time(s) E P t

  20. Energy Consumption Pg. 308

  21. Paying Power for Electricity is measuredin kW•h Complete 9-2Bpg. 310

  22. Careers related to Electricity •Electrician •Photocopiertechnician

  23. ElectricalEfficiency Electrical energy maybe converted such as: to other forms 1. 2. 3. Light Heat Sound

  24. Efficiencyis the% of energy that is form. converted to auseful Efficiency =usefulenergyoutput x100 totalenergyinput Completepracticeproblemspg.318

  25. EnerGuide Labels •Detailshowmuch energyan appliance usesinayearandcomparestootherappliances.

  26. Reducing Electrical Consumption •Improveinsulationof home •Turnoff lightswhen notin use •Use energy efficientlight bulbs •Airdry clotheswhen possible

  27. CORE STSE “Electricity Conservation: The New Trend”

  28. Energy Generators •Electrical generator up of a coil of wire and amagnet) (made

  29. Electrical Generating Stations 1. 2. 3. Hydroelectric Thermal Nuclear See pg. 327

  30. Getting Power… *Transformersareelectrical thatchangevoltagesothat devices itcanbe usedbyhomes.(120Vand240V)

  31. Problems? 1.Safety 2.Cost of 3.Degree impact production of environmental

  32. Alternate Energy Sources •Windgenerators

  33. •Solarenergy

  34. •Fuel cells

  35. Constraints to New Technologies 1. 2. 3. Cost Availabilityof materials Properties of materials Seepg. 330-4

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