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Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
Form 3 PMR Science Chapter 7 Electricity
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Form 3 PMR Science Chapter 7 Electricity

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Form 3 PMR Science Chapter 7 Electricity

Form 3 PMR Science Chapter 7 Electricity

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Transcript

  • 1. Chapter 7
  • 2. Generation of electricity• Chemical cells• Convert chemical energy to electrical energy• Zinc and Copper plate
  • 3. Dry cells
  • 4. Lithium ion, Nickel Cadmium cell
  • 5. Lead acid accumulator• Car battery• Converts chemical energy to electrical energy• Rechargeable
  • 6. Generation of Electricity• Bicycle Dynamo• Kinetic energy to electrical energy
  • 7. Solar cell• Convert light energy to electrical energy
  • 8. Electric Current• Caused by the flow of negative charges along a conductor
  • 9. Why negative charges move?• Due to potential difference between 2 points of a conductor• Potential difference = Voltage Electrons move from region of Higher electron concentration to region of Lower electron concentration.
  • 10. Make sure you can differentiate electric
  • 11. How much negatively-charged electrons are moving along aconductor at a particular time?
  • 12. What is current? • Flow of electrons along a conductor
  • 13. How does electrons move along a conductor??
  • 14. How to measure electric current?• Ammeter• Milliammeter• Connect in series (one by one)• Positive terminal ammeter – positive terminal battery• Negative terminal ammeter – negative terminal battery
  • 15. Ammeter• Measures electric current• SI unit for current = Ampere (A)How to measure?? One after another – Series circuit
  • 16. • The brighter the light bulb, the higher the reading of ammeter.
  • 17. What are the differences between these circuits?
  • 18. What is voltage?• Voltage is provided by the electrical sources• Eg. Battery, lead acid accumulator
  • 19. Voltage• Potential difference across 2 points
  • 20. Voltage• Measure potential difference (Voltage) between 2 points• SI unit – Volt (V)• How to connect?To measure voltage of a light bulb,we have to connect the voltmeter acrossthe light bulb – Parallel circuit
  • 21. • The brighter the light bulb, the higher the reading of voltmeter.
  • 22. Resistor• To restrict current flow• Used in - Radio, Television, Oven, Fan
  • 23. Resistance reduces current flow
  • 24. The greater the resistance the smaller the current flows
  • 25. Electric circuit components
  • 26. All materials haveelectrical resistanceResistance =Frictional forceOpposes the direction of current flowGood electrical conductor = Low resistancePoor electrical conductor = High resistance
  • 27. Factors affecting resistance• The length of the wire – The longer the wire, the greater the resistance• The thickness of the wire – The thicker the wire, the lesser the resistance• The type of material used – Different types of materials have different resistances • Copper and Silver • Iron and Magnesium
  • 28. Factors affecting resistance• The length of the wire – The longer the wire, the greater the resistance
  • 29. Factors affecting resistance• The thickness of the wire – The thicker the wire, the lesser the resistance
  • 30. • The thickness of the wire – The thicker the wire, the lesser the resistance
  • 31. Factors affecting resistance• The type of material used – Different types of materials have different resistances
  • 32. Relationship between current and resistance• High resistance >>>> _____ current• Low resistance >>>> _____ current Length of nichrome wire Ammeter reading 20 0.9 30 0.7 40 0.5 50 0.3 60 0.1
  • 33. Relationship between voltage and current• Imagine voltage as battery• Higher voltage >>> Greater current• Lower voltage >>> Lesser current
  • 34. ResistanceOhm’s law – Current (I) that flows through a metal conductor is directly proportional to the potential difference (voltage) across it, if resistance remains constant
  • 35. Relationship betweenCurrent, Voltage and Resistance
  • 36. Series and Parallel circuit• Series – One way traffic• Parallel – More than one way
  • 37. • When more light bulbs are added, the brightness of light bulb decreases.
  • 38. Advantages & Disadvantages of Series Circuit – One switch can switch off everything
  • 39. Parallel circuit• Each bulb receive full voltage from battery and have same brightness
  • 40. Advantages and disadvantages of Parallel circuit• Other electrical appliances can still function if one of them break down
  • 41. Parallel circuitSame brightness

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