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7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
7.5 electrical energy and power
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7.5 electrical energy and power

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SPM Malaysia Physics Syllabus Chapter 7: Electricity Part 5: Electrical Energy and Power

SPM Malaysia Physics Syllabus Chapter 7: Electricity Part 5: Electrical Energy and Power

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  • 1. Chapter 7: ElectricityElectrical Energy and Power
  • 2. The ability of the electriccurrent to do work
  • 3. Electrical Energy Supplied by a source of electricitySuch as a cell or battery When current flows in a closed circuit
  • 4. Electrical Energy Converts into other forms such as: heat light mechanicalBy electrical appliances when current flows in it
  • 5. Potential Difference, V Energy, E transferred by 1 C of charge, Q that moves between two points
  • 6. CurrentRate of charge flow
  • 7. Combining these two equations, we get
  • 8. PowerUnit = Watt (W)
  • 9. An Electric Kettle Marked 240 V 1500 W Means that the kettle consumes 1500 J of electrical energy every second its connected to 240 V
  • 10. The larger the power rating,the more energy consumed in every second. The longer the usage time, the more electrical energy is consumed.
  • 11. 1 kilowatt-hour (kWh) The amount of energy consumed by an electrical applianceIn 1 hour At the rate of 1 kilowatt
  • 12. 1 kWh = 1 unit of energy1 kWh 3.6 x 106 J 1 kW x 1 hr 100 W x 3600 s
  • 13. Efficiency Percentage of output power to the input power
  • 14. The efficiency of an electrical appliance Is always less than 100%Because some energy is lostthe form of heat and sound
  • 15. Energy EfficiencyUsing energy efficient devices to gain a higher level of useful outputs using less input
  • 16. Increasing energy efficiency Reduces costs And also assisting in energy conservation
  • 17. Energy efficient lightings Use compact fluorescent bulbs instead of regular incandescent bulbs
  • 18. Utilize electrical appliances wiselyRun washingmachines onfull load only
  • 19. Utilize electrical appliances wisely Iron clothes inbulk (i.e. severalpieces at a time)
  • 20. Utilize electrical appliances wisely Limit usage or air conditioning and lighting Switch them off when you leave the room
  • 21. Utilize electrical appliances wiselyClean air filters in air conditioners and clothes dryers regularly
  • 22. Utilize electrical appliances wiselyDefrost refrigerators regularly – so that your freezer don’t work so hard
  • 23. Utilize electrical appliances wisely Improve ventilation and air flow Better ventilation reduces cooling load of air conditioners
  • 24. A fuse – a short piece of thin wireWhich overheats when current above a certain value flows through it
  • 25. The fuse melts when a current that is too high flows during a short circuitThis prevents overheating of the wire which would cause a fire
  • 26. If power rating of an appliance is960 W and 240 V, then normal current = 4 A Fuse to be used must be of higher current:- so use 5 A fuse
  • 27. Earth Wire, E Three Pin Plug (green) Safety wire – connects appliance to earth Live Wire, L (brown)Neutral Wire, Current flows N (blue) through circuitZero Potential Difference
  • 28. Three Pin Plug If a Live Wire touches the metal body of the appliance, a large current would immediately flow to the earth and breaks the fuse. This will avoid someone from being electrocuted.
  • 29. Pic credits• Flickr / Plug Face - Day 3/365 / Jake Mates • Flickr / 148:365 - 09/25/2012 - Blown Fuse / Shardayy• Flickr / Plasma 5/ limowreck666 • Flickr / Con – Fused / canonsnapper• Flickr / Pedagaggi Wind Turbines / Sebastiano • Flickr / Wiring a Plug / tjmwatson Pitruzzello• Flickr / Dying moments / limowreck666• Flickr / defying murphy’s law / vakas• Flickr / Vintage Blackboard / pareerica• Flickr / Ultraman + Mt. Fuji = JAPAN / emrank• Flickr / kettle / butkaj.com• Flickr / March of the washer-dryers / Worldislandinfo.com• Flickr / 3D Green Energy / StockMonkeys.Com• Flickr / Electric Fuel Cap - RAC Future Car Challenge / Dominic Alves• Flickr / Fluorescent Tube / jeancliclac• Flickr / 154/366 / hannah8ball• Flickr / untitled / John Steven Fernandez• Flickr / kitty TV / kassandrapoised• Flickr / Universal Iron and Drapery / firexbrat• Flickr / Only in Egypt / mnadi• Flickr / This means you!! / passiveaggressivenotes• Flickr / thefreezerstaresatme / expressionposthumus• Flickr / cityswing / i_gallagher• Flickr / made in england / fishyfish_arcade

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