| Method |
Precise Learning Objective |
Linked |
Question / Activity
(Designed for maximum working out) |
Stepping Stones |
Pitstop Check
(Thinking Map) |
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Mains electricity is an ac supply.
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What type of supply is mains electricity? |
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In the United Kingdom the domestic electricity supply has a frequency of 50 Hz. |
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What is the frequency of the domestic electricity supply in the United Kingdom? |
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[In the United Kingdom the domestic electricity supply] is about 230 V. |
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What is the potential difference of the domestic electricity supply in the United Kingdom? Demonstrate alternating current and direct current with pupil electrons
or a long loop of string |
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Students should be able to explain the difference between direct and alternating potential difference. |
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What is the difference between direct and alternating potential difference? Research the use of direct and alternating potential difference. Find out why the USA used direct potential difference, then changed to an alternating potential difference.. |
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Most electrical appliances are connected to the mains using three-core cable. |
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How many core cables do most electrical appliances use to the mains? Demo to take apart a plug and sketch how it is wired. Then research the role of each part of the plug
- Plastic casing
- Insulated cable
- Fuse
- Live wire
- Neutral wire
- Earth wire |
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The insulation covering each wire is colour coded for easy identification:
live wire ? brown
neutral wire ? blue
earth wire ? green and yellow stripes. |
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Why is the insulation covering of each wire in a plug colour coded? What colour is the
a) Live wire
b) Neutral wire
c) Earth wire |
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The live wire carries the alternating potential difference from the supply. |
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What is carried by the live wire from the supply? |
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The neutral wire completes the circuit. |
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What completes the circuit in a plug? |
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The potential difference between the live wire and earth (0 V) is about 230 V. |
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What is the potential difference between live wire and earth wire? |
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The neutral wire is at, or close to, earth potential (0 V). |
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Which wire in a plug is at, or close to, earth potential (0 V)? What safety measures are used with mains electricity? |
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The earth wire is at 0 V, it only carries a current if there is a fault. |
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What is the potential difference of the earth wire in a plug, and when would it carry a current? |
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Students should be able to explain that a live wire may be dangerous even when a switch in the mains circuit is open |
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When might a live wire still be dangerous when considering a switch? |
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Students should be able to explain the dangers of providing any connection between the live wire and earth. |
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What are the dangers of providing any connection between the live wire and earth? |
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The earth wire is a safety wire to stop the appliance becoming live. |
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What is the purpose of the earth wire? |
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