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

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

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