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GCSE - LV D > Paper 1 - 2b Domestic Electricity > Flashcards

Paper 1 - 2b Domestic Electricity Flashcards

1
Q

State the typical voltage for mains electricity?

A

230 V

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2
Q

State the frequency of mains electricity

A

50 Hz

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3
Q

Define a.c.

A

Alternating current, the electrons vibrate backwards and forwards. Mains electricity use a.c.

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4
Q

Define d.c.

A

Direct current. Electrons only flow in one direction. This is what we get from batteries

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5
Q

State the names and colours of the 3 wires found inside a cable.

A

Live wire - Brown Neutral wire - Blue Earth wire - Green and yellow stripes

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6
Q

Which pin is the earth wire connected to?

A

The top pin

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7
Q

Which pin is the live wire connected to?

A

The bottom right pin

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8
Q

Which pin is the neutral wire connected to?

A

The bottom left pin

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9
Q

Where is the fuse in a plug?

A

Between the live pin and the live wire

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10
Q

What is the role of the fuse?

A

If current gets too high the fuse melts and breaks the circuit, cutting off the live wire

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11
Q

How does the earth wire work with the fuse?

A

The earth wire is connected to a metal case. When there is an electrical fault, the live wire may also touch the metal case. This creates a parellel circuit. The earth wire has a low resistance. This increases the current drawn from the power supply, which melts the fuse on the live wire. This breaks the circuit and stops the metal device becoming live.

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12
Q

Why is the wire made of copper?

A

As copper conducts electricity and is ductile.

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13
Q

Why are pins made of brass?

A

As brass conducts electricity, do not rust and are hard to change shape.

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14
Q

Why is the plug made of stiff plastic?

A

As it is an insulator and it’s hard to change shape

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15
Q

What does the cable grip do?

A

It prevents the wires from snapping if tension is applied to the cable

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16
Q

Why do some electrical devices not have an earth wire?

A

As they are double insulated

17
Q

Which wire can be missing from some appliances? Why?

A

Earth wire, if the appliance is plastic and you cannot get an electric shock from it.

18
Q

State the role of the live wire

A

To carry the alternating potential difference from the supply to the component. the potential difference between the live and the earth is 230 V

19
Q

State the role of the neutral wire

A

The neutral wire complete the circuit from the component back to the supply. The neutral wire is at or close to 0 V.

20
Q

State the role of the earth wire.

A

It is a safety wire to stop an appliance becoming live. the earth wire is at 0V as it only carries a current if there is a fault.

21
Q

State the relationship between power, potential difference and current.

A

Power = potential difference x current (P = VI)

22
Q

State the units of power

A

Watts (W)

23
Q

State the units of potential difference

A

Volts (V)

24
Q

State the units of current

A

Amperes (A)

25
Q

State the relationship between power, resistance and current.

A

Power = (Current)squared x resistance

26
Q

State the units for resistance

A

Ohms

27
Q

When using an electrical device what factors affect how much electrical energy it uses?

A
  1. Time it is used for 2. The power of the appliance
28
Q

State the equation between energy transferred, power and time

A

Energy transferred (J) = Power (W) x time (s)

29
Q

State the equation between energy transferred, charge and potential difference

A

Energy transferred (J) = Charge (C) x potential difference (V) E = QV

30
Q

State the parts that make up the national grid

A

Cables, step up transformers, step down transformers

31
Q

What does a step up transformer do? Why?

A

Increases the potential difference, which decreases the current. This reduces the amount of energy lost to heat so makes them more efficient.

32
Q

What does a step down transformer do? Why?

A

Decreases the potential difference which increases the current. This makes them safer to use in homes.

GCSE - LV D (11 decks)

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