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Year 7 Science > 7E Electromagnets > Flashcards

7E Electromagnets Flashcards

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1
Q

What is a circuit symbol?

A

A diagram used to represent a component

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2
Q

What represents a wire in a circuit diagram?

A

A straight line

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3
Q

What is a cell?

A

The power source in a circuit ( what we usually call a battery)

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4
Q

What is a battery?

A

Two or more cells

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5
Q

Why do we use circuit diagrams?

A

To make it easier to see what is connected to what in a circuit

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6
Q

What should you use to draw a circuit diagram?

A

Use a pencil and ruler, use correct symbols

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7
Q

What should you draw first when drawing a circuit diagram?

A

The symbols

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8
Q

What is a lamp?

A

Another name for a bulb

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9
Q

What has to happen for a circuit to work?

A

All components must be connected

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10
Q

How does a switch work?

A

It causes two pieces of metal to touch and complete the circuit

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11
Q

What makes a lamp light up?

A

Current passing through it

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12
Q

What does the battery do in a circuit?

A

It makes the current flow around the circuit

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13
Q

Why does a higher voltage affect the brightness of a bulb?

A

It creates a higher current, so the bulb is brighter

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14
Q

What is current?

A

Flow of electric charge

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15
Q

Why does charge all start moving at the same time?

A

The charge is evenly spread through the wires

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16
Q

What must a circuit always contain?

A

A power supply, no gaps

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17
Q

What do you use to measure the potential difference of a cell or a battery?

A

Using a voltmeter

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18
Q

What is the potential difference of the mains electricity?

A

230V

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19
Q

What happens if there is an increase in the voltage?

A

A bigger push and a bigger current

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20
Q

What does potential difference actually mean?

A

The difference in energy between two different points in the circuit

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21
Q

How do you increase the potential difference in a circuit?

A

Increasing the power supply

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22
Q

How does the voltmeter need to be connected in a circuit?

A

In a parallel circuit

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23
Q

What is the potential difference in a circuit with 3 1.5V cells?

A

4.5V

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24
Q

What might happen to a lamp when you add more cells?

A

It will get brighter

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25
Q

What is an electrical conductor?

A

A material that allows electricity to pass through easily

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26
Q

Give 2 examples of conductors.

A

Any names metal, graphite

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27
Q

What is an electrical insulator?

A

A material that does not allows electricity to pass through easily

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28
Q

Give 2 examples of insulators.

A

Plastic, rubber, glass

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29
Q

What is resistance?

A

The opposition to the movement of electrical charge

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30
Q

WHat are the units that resistance are measured in?

A

Ohms (Ω)

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31
Q

What is the relationship between current and resistance?

A

Higher current = lower resistance

32
Q

Name 2 factors that can affect resistance?

A

Material, length of wire, thickness of wire, temperature

33
Q

Which type of circuit will have only one pathways for current to flow?

A

Series

34
Q

Describe the structure a series circuit.

A

Components connected end to end in a loop.

35
Q

Describe the structure of a parallel circuit.

A

Components connected side by side in different loops.

36
Q

Explain why the voltage and current might be different in the two types of circuit

A

In series there is only 1 pathway for the electricity to follow, in parallel there can be many.

37
Q

What is the rule for p.d in a series circuit?

A

Potential difference is shared across each component.

38
Q

How do you calculate resistance in a series circuit?

A

Add the resistance from each resistor.

39
Q

What is the rule for p.d in a series circuit?

A

Potential difference is the same across each loop.

40
Q

What is the rule for resistance in a parallel circuit?

A

the total resistance of the circuit is reduced as the current can follow multiple paths

41
Q

What does current do?

A

Transfers energy in a circuit

42
Q

What are the two types of current?

A

Alternating and direct

43
Q

How are the two types of current different?

A

Direct only goes in one direction alternating continually reverses

44
Q

What are electrons?

A

Negative charged particles

45
Q

What is the difference between a series and parallel circuit?

A

Series is one loop parallel is many

46
Q

What is a problem with series circuits?

A

One component goes and the current cannot flow

47
Q

What is an advantage of series circuits?

A

Less wires

48
Q

Why are homes wired with parallel circuits?

A

If one bulb goes the others keep working

49
Q

What is resistance?

A

A measure of the opposition of flow of electricity

50
Q

What does the symbol represent?

A

Ohms

51
Q

State the calculation for resistance

A

Resistance = potential difference/ current

52
Q

Rearrange the calculation to find current:

A

Current = potential difference/ resistance

53
Q

What is Ohms law?

A

When resistance stays the same potential difference and and current are directly proportional

54
Q

How do you connect a voltmeter in a circuit?

A

In parallel

55
Q

How do you connect an ammeter in a circuit?

A

In series

56
Q

What does the term directly proportional mean?

A

As one variable increases the other increases by the same amount

57
Q

Does electrical current flow more easily in air or water?

A

In water

58
Q

Why is it dangerous to play around overhead wires?

A

The electricity could pass through your body if you come into contact with the wires

59
Q

What can an electrical shock do to your body?

A

It can affect your muscles and nerves, paralyse you or stop your heart.

60
Q

What colour is the earth wire in a plug?

A

Green and yellow striped

61
Q

What is the function of the live wire in the plug?

A

It carries the electrical current

62
Q

What is the function of the neutral wire in a plug?

A

It completes the circuit

63
Q

How does a fuse work?

A

It contains a thin wire that melts if current is too high

64
Q

Why are the outer casings of electrical appliances covered in plastic?

A

It is an insulator (electricity will not pass through)

65
Q

What is a theory?

A

Explanation to explain an phenomena

66
Q

What is a model?

A

Helps visualise things that cannot be seen

67
Q

Why do we use models?

A

Help understand ideas

68
Q

When should we use models?

A

After the scientific explanation

69
Q

What is an electric field?

A

Area around a charged object where a force can be felt

70
Q

What causes an electric field?

A

A charged object

71
Q

What 2 things can happen in an electric field?

A

Objects can attract or repel

72
Q

Why can the 2 things happen in an electric field?

A

Like charges will push away from each other, opposite charges will pull towards each other

73
Q

What direction does an electric field occur in?

A

From positive to negative charges

74
Q

What might happen as you move away from the charge?

A

Effect is less, force gets weaker

75
Q

What does the comb in a Van de Graaff generator do?

A

Is given a positive voltage to attract electrons from the belt

76
Q

Why do hairs stick out in every direction if you touch the VdG generator?

A

They repel the scalp and each other

Year 7 Science (11 decks)

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