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Physics: P2 > P2.4 Using mains electricity safety and the power of electrical appliances > Flashcards

P2.4 Using mains electricity safety and the power of electrical appliances Flashcards

1
Q

What current do cells and batteries supply?

A

Current that always passes in the same direction, this is called direct current

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2
Q

What is an alternating current?

A

One that is constantly changing direction

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3
Q

What is the period of an AC supply?

A

The time taken for one complete oscillation. You can find the period by looking at the time taken between one peak/trough and the next

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4
Q

What is the frequency of an AC supply?

A

The number of oscillation per second. You can find it by dividing one by the period

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5
Q

What is an example of an AC supply?

A

Mains electricity

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6
Q

What frequency does the UK mains electricity have and what voltage?

A

Frequency of 50 cycle per second (50 hertz) and is about 230 V

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7
Q

How are most electrical appliances connected to the mains?

A

Using cable and a three pin plug

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8
Q

How many wires does a cable have?

A

Two or three

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9
Q

What is the core in a cable made of?

A

Copper, it is good at conducting electricity

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10
Q

What are the outer layers made up of?

A

Flexible plastic, because plastic is a good electrical insulator

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11
Q

What is the blue wire?

A

The neutral wire

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12
Q

What is the brown wire?

A

The live wire

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13
Q

What is the green and yellow striped wire?

A

The earth wire

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14
Q

What is the case of a plug made up of?

A

Tough plastic or rubber, good electrical insulators

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15
Q

What are the three pins made up of?

A

Brass, good electrical conductor

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16
Q

What is there between the live terminal and the live pin?

A

A fuse

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17
Q

What is a fuse?

A

A fuse breaks the circuit if too much current flows

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18
Q

What is the cable secured in the plug by?

A

A cable grip

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19
Q

Where does the blue wire go?

A

The bLue wire goes to the left

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20
Q

Where does the brown wire go?

A

The bRown wire goes to the right

21
Q

Where does the striped wire go?

A

The sTriped wire goes to the top

22
Q

If an electrical fault causes too great a current, what happens?

A

The circuit is disconnected by a fuse or a circuit breaker in the live wire

23
Q

When the current in a fuse wire exceeds the rating of the fuse it will…

A

Melt, breaking the circuit

24
Q

What are some circuits protected by?

A

Residual Current Circuit Breakers (RCCB)s

25
Q

How do RCCBs operate?

A

By detecting a difference in the current between the live wire and neutral wires

26
Q

RCCBs operate much…

A

Faster than a fuse

27
Q

What are appliances with metal cases often?

A

Earthed

28
Q

Appliances without a earth wire are what instead?

A

Double insulated

29
Q

What do the earth wire and the fuse do together?

A

Protect the circuit

30
Q

What are the most common fuse ratings?

A

3A, 5A and 13A

31
Q

The thicker the wire in the fuse…

A

The higher the fuses rating

32
Q

What happens when an electrical charge flows through a resistor?

A

It gets hot

33
Q

A lot of energy is lost in filament bulbs by…

A

Heating

34
Q

Less energy is wasted in power saving lamps such as…

A

Compact Fluorescent Lamps (CFLs)

35
Q

What is power?

A

The rate at which energy is transferred by an appliance

36
Q

What is the equation for power?

A

E
P = —–
t

37
Q

What is power measured in?

A

Watts

38
Q

What does the P stand for?

A

Power

39
Q

What does the E stand for?

A

Energy

40
Q

What does the t stand for?

A

Time

41
Q

What is the equation for power, potential difference and current?

A

P = I x V

42
Q

What does the I stand for?

A

Current

43
Q

What does the V stand for?

A

Potential difference

44
Q

What is current measured in?

A

Amps

45
Q

What is the potential difference measured in?

A

Volts

46
Q

Through calculating the current of an appliance what can we determine?

A

The size of fuse needed

47
Q

What is the equation for energy transferred, potential difference and charge?

A

E = V x Q

48
Q

What does Q stand for

A

Charge

49
Q

What is charge measured in?

A

Coulombs

Physics: P2 (6 decks)

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