Andries 4 energy and change

820 views

Published on

Gr. 9 Natural Science South Africa NCS syllabus. Taken from Andries Olivier.

Published in: Education, Technology, Business
0 Comments
1 Like
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
820
On SlideShare
0
From Embeds
0
Number of Embeds
211
Actions
Shares
0
Downloads
35
Comments
0
Likes
1
Embeds 0
No embeds

No notes for slide

Andries 4 energy and change

  1. 1. Energy and change
  2. 2. Mechanical systems to electrical
  3. 3. Van der graaff
  4. 4. dynamo
  5. 5. Alternative sources
  6. 6. Electricity from nonrenewable sources
  7. 7. Coal
  8. 8. Electricity from renewable sources
  9. 9. Wind
  10. 10. Solar energy
  11. 11. Biomass/Biogas
  12. 12. Waterfalls
  13. 13. Geothermal
  14. 14. Wave energy
  15. 15. Tidal energy
  16. 16. Nuclear energy
  17. 17. cells
  18. 18. Store energy as chemical potential energy This is converted to electric energy when the battery/cell is connected to an appliance. R e m e m b cell battery
  19. 19. Inside the cell is a liquid called an electrolyte. Consist of millions of ions Two electrodes are suspended in the electrolyte. Two different electrodes cause a + pole and a – pole, just like a battery.
  20. 20. How does a battery work? Measured in volts Electricity will flow from the – to the + when a circuit is connected. The difference in charge is called potential difference
  21. 21. There must be a potential difference in an electric circuit for electricity to flow.
  22. 22. Wet and dry cells
  23. 23. The type of cell in the previous slides is a wet cell.
  24. 24. The type of cell in toys, radios and torches are called dry cells.
  25. 25. Flow of current as movement of charge.
  26. 26. Electric current is the movement of charge.
  27. 27. Direction (Conventional current)
  28. 28. The flow of positive charge from the positive pole of a cell to the negative pole of a cell through an external conductor.
  29. 29. Electric current is the opposite and flows from negative to positive.
  30. 30. We always use conventional current.
  31. 31. Coulomb (unit of charge)
  32. 32. Does your mum buy milk by the drop?
  33. 33. She buys it by the litre, because counting the drops will take forever!
  34. 34. In the same way, we count electrons in bundles. The unit of charge is thus a large amount of electrons together, called The coulomb. 1 coulomb = 6 250 000 000 000 000 000 = 6,25 x 1018 particles
  35. 35. The ammeter is used to measure how quickly charge flows past a fixed point in a conductor.
  36. 36. The ammeter is … Always connected in series in a circuit. Always connected positive to positive, and negative to negative.
  37. 37. Ampere (unit of current)
  38. 38. Q = It Charge in coulomb (C) Current in ampere (A) Time in seconds (s)
  39. 39. A coulomb is the amount of charge that flows past a certain point in a conductor in one second when the current that flows through it is one ampere.
  40. 40. voltmeter
  41. 41. Potential difference or electric charge - Ability of a cell to deliver electric current. Measured in volt (V)
  42. 42. The voltmeter is... always connected in parallel. connected positive to positive and negative to negative.
  43. 43. A V V
  44. 44. Resistance
  45. 45. Things that allow current to flow through them are called conductors.
  46. 46. Things that don't allow the flow of current through them are called insulators.
  47. 47. Collisions between the charges and the particles of the conductor obstruct the flow of charge. This is called resistance.
  48. 48. Electrical resistance is the Obstruction a conductor offers against the flow of charge.
  49. 49. Ohm's law
  50. 50. Potential difference (V), in a simple electric circuit, is equal to the current strength (I) multiplied by the resistance (R).
  51. 51. V = IR Potential difference (V) Current in ampere (A) Resistance in ohm (Ω)
  52. 52. Potential difference (V), in a simple electric circuit, is equal to the current strength (I) multiplied by the resistance (R).
  53. 53. Factors that determine the resistance of a conductor Andries p 165
  54. 54. Factors that influence the resistance of a conductor: Type Length Thickness Temperature
  55. 55. Type
  56. 56. Length
  57. 57. Thickness
  58. 58. Temperature
  59. 59. Series circuit
  60. 60. Parallel circuit
  61. 61. If the potential difference increases, the current increases
  62. 62. If the resistance increases, the current strength decreases
  63. 63. Main current divides between parallel connected branches. Ammeter readings are the sameall over the circuit. Current in series and parallel
  64. 64. Potential difference is the sameeverywhere in a parallel connection. Potential difference dividesbetween the resistors. Pd in series and parallel
  65. 65. Increased amount of resistors = increased total resistance Increased amount of resistors = decreased total resistance Resistors in series and parallel
  66. 66. Increased total resistance Decreased total resistance Resistors in series and parallel
  67. 67. Current in each resistor is the same Current divides. Depends on the magnitude of the resistance Resistors in series and parallel
  68. 68. Vt = V1 + V2 Vt = V1 = V2 Resistors in series and parallel

×