Physics P2 5.2 Cables and plugs.

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What are sockets and plugs made of?
Stiff plastic materials which enclose the electrical connections.
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What do cables consist of?
Two or three insulated copper wires surrounded by an outer layer of flexible plastic material.
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What are there in a three-pin plug or a three-core cable?
The live wire which is brown, the neutral wire which is blue and the earth wire which is green and yellow.
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What is the earth wire used for?
To earth the metal case of a mains appliance.
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What are most electrical appliances connected to?
The sockets of the mains supply using cable and a three-pin plug.
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Why is the outer cover of a three-pin plug made of plastic or rubber?
Both these materials are goo electrical insulators.
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What re the pins of a plug made of and why?
Brass because brass is a good electrical conductor and is also hard and will not rust or oxidise.
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Which pin is the earth wire connected to?
The longest pin.
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What is it important to check on a plug?
That the cable grip is fastened tightly over the cable, there should be no bare wires showing inside the plug and the correct cable must be connected firmly to the terminal of the correct pin.
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What is missing from a two-core cable?
The earth wire.
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Why don't some appliances need an earth?
Because they have plastic cases therefore they are said to be double insulated and are connected to the supply with two-core cable containing just a live and a neutral wire, appliances with metal cases must be earthed.
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How is an appliance with a metal case earthed?
The case is attached to the earth wire in the cable.
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Why do cables come in different thicknesses?
Cables of different thicknesses are used for different purposes, the more current to be carried the thicker the cable needs to be.
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Why are the pins of a plug made of brass?
Brass is a good conductor and does not rust or oxidise.
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Why must appliances with metal cases be earthed?
So that the case cannot become live and electrocute you.
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**MAKE SURE THAT YOU CAN IDENTIFY FAULTS IN THE WIRING OF A THREE-PIN PLUG**
**LOOK UP MAINS CABLE AND THE INSIDE OF A THREE-PIN PLUG**
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Other cards in this set

Card 2

Front

What do cables consist of?

Back

Two or three insulated copper wires surrounded by an outer layer of flexible plastic material.

Card 3

Front

What are there in a three-pin plug or a three-core cable?

Back

Preview of the front of card 3

Card 4

Front

What is the earth wire used for?

Back

Preview of the front of card 4

Card 5

Front

What are most electrical appliances connected to?

Back

Preview of the front of card 5
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