P4 - Safe Electricals

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What is the name of a device that changes resistance?
Rheostat or variable resistor
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How can you make the wire have more resistance?
By making it a longer length or thinner
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What is voltage measured in?
Volts (V)
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How is voltage measured?
Using a voltmeter connected in parallel
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For a fixed resistor, as the voltage across it increases...
the current increases
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For a fixed power supply, as the resistance increases...
the current decreases
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What is the formula for resistance?
resistance = voltage / current
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What is resistance measured in?
Ohms
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What does the live wire do?
Carries a high voltage around the house
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What does the neutral wire do?
Completes the circuit, providing a return path for the current
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What is the main purpose of fuses and earth wires?
Stop a person receiving an electric shock if they touch a faulty appliance. As soon asthe case becomes 'live', a large current flows in the earth and live wires and fuse 'blows'
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What does the earth wire do?
Is connected to the case of an appliance to prevent it becoming live
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What does the fuse do?
Contains wire which melts, breaking the circuit, if the current becomes too large
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What happens if the fuse melts the wire? How is restored?
Doesn't need to be replaced to restore power, it can be re-set
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What is power?
The rate at which an appliance transfers energy
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Other cards in this set

Card 2

Front

How can you make the wire have more resistance?

Back

By making it a longer length or thinner

Card 3

Front

What is voltage measured in?

Card 4

Front

How is voltage measured?

Card 5

Front

For a fixed resistor, as the voltage across it increases...