Electricity - Domestic Electricity Flashcards

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1
Q

what is the voltage of the uk domestic mains supply

A

230

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2
Q

what uses direct current

A

cells and batteries

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3
Q

what is the colour and role of the live wire

A

brown

provides alrwernating pd

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4
Q

what is the colour and role of the neural wire

A

blue

completes circuit and carries away current

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5
Q

what is the colour and role of the earth wire

A

yellow and green

stops appliance becoming live

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6
Q

what happens when you touch the live wire

A

large pd across body and current flows through you which causes an electric shock. you create a connection between the live wire and the earth

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7
Q

why is it dangerous to touch a live wire if the plug is turned off

A

still pd across wire

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8
Q

why is energy transferred when a charge flows

A

because charge does work against the resistance of the circuit

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9
Q

what is the equation for energy transferred using power

A

= power x time

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10
Q

what does a power rating tell you

A

maximum amount of energy transferred between stores per second

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11
Q

why may an appliance with more power not transfer energy usefully

A

bad efficiency

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12
Q

describe the rise and fall in pd of of charge as it moves around a circuit

A

charge gains energy at battery , increasing pd.

charge releases energy at resistors, dropping the voltage

these are rises and falls

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13
Q

energy transferred = charge x potential difference

A

a bigger change in pd means more energy is transferred

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14
Q

what is the national grid

A

network of cables and transformers that connect power stations to consumers

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15
Q

why is a low current used in the national grid

A

wires heat up and energy is lost when current is high

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16
Q

what is a transformer

A

changes pd of electrical supply

17
Q

what voltage is the electricity in electricity cables at

A

400 000 v

18
Q

how can power stations adapt to changes in demand

A

run well below their maximum power output