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GCSE Revision Flashcards > P2 Electricity > Flashcards

P2 Electricity Flashcards

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1
Q

What is alternating current?

A

Electric current in a circuit that repeatedly changes direction

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2
Q

What is direct current?

A

Electric current in a circuit that flows in one direction only

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3
Q

What is power?

A

The energy transformed or transferred per second

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4
Q

What is the unit for power?

A

Watts, W

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5
Q

What is efficiency?

A

Useful energy transferred by a device / total energy supplied to a device

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6
Q

What is potential difference?

A

A measure of the work done or energy transferred between 2 points in an electrical circuit

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7
Q

What is the unit for potential difference?

A

Volts, V

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8
Q

What is the national grid?

A

The network of cables and transformers used to transfer electricity from electricity producers to electricity consumers

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9
Q

What is the unit for energy?

A

Joules, J

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10
Q

What are the 3 equations to calculate power?

A
  1. Power = Energy / Time (P = E / T) - PET
  2. Power = Current x Voltage (P = I x V) - Penguins in Vegas
  3. Power = Current^2 x Resistance (P = I^2 x R) - Penguins in a square room
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11
Q

What are the 2 equations to calculate energy?

A
  1. Energy = Power x Time (E = P x T)
  2. Energy = Charge x Voltage (E = Q x V) - Every Queen Vacuums
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12
Q

What are the 2 equations to calculate efficiency?

A
  1. (useful energy out / total energy in) x 100
  2. (useful power out / total power in) x 100
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13
Q

What colour is the live wire?

A

Brown

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14
Q

What is the function of the live wire?

A

Carries a current that alternates between negative and positive voltage - current flows in through

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15
Q

What colour is the earth wire?

A

Green/yellow

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16
Q

What is the function of the earth wire?

A

A safety feature that is needed to earth electrical appliances with metal casing. This makes it safer to touch an appliance if it develops a fault - only has current if there is a fault

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17
Q

What is the function of the neutral wire?

A

Completes the circuit. Kept at 0 voltage by the electricity company - current flows out through

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18
Q

What colour is the neutral wire?

A

Blue

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19
Q

What is the function of the fuse in a plug?

A

Can melt (blow) if too much current flows through - breaks the circuit

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20
Q

What type of supply is mains electricity?

A

a.c. supply

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21
Q

What is the voltage of mains electricity?

A

230V

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22
Q

What is the frequency of mains electricity?

A

50Hz

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23
Q

What does the frequency of mains electricity mean (50Hz)?

A

That it changes direction and back again 50 times a second (analogue signal graph)

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24
Q

What does directly proportional mean?

A

Double one, doubles the other

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25
Q

What does inversely proportional mean?

A

Double one, halves the other

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26
Q

What does a diode do?

A

Only lets current flow one direction - very high resistance in the ‘wrong direction’

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27
Q

What is current measured in?

A

Amps, A

28
Q

What is charge measured in?

A

Coulombs, C

29
Q

What is potential difference?

A

Difference in energy between 2 points

30
Q

What is the function of a thermistor?

A

Changes resistance with temperature - higher temp = lower resistance

31
Q

What is the function of a variable resistor?

A

We can manually change the resistance

32
Q

What is the function of a fixed value resistor?

A

Always has the same resistance value

33
Q

What is resistance?

A

How hard it is for current to flow

34
Q

What are the 2 types of circuit?

A

Series and parallel

35
Q

Explain current in a series circuit:

A

Current same at every point in a series circuit

36
Q

Explain current in a parallel circuit:

A

Total current in a parallel circuit = sum of currents through the separate components

37
Q

Explain p.d. in a series circuit:

A

Total p.d. of power supply is shared between the components

38
Q

Explain p.d. in a parallel circuit:

A

p.d across each component is the same

39
Q

Explain resistance in a series circuit:

A

More resistors, greater the resistance. Total resistance of 2 components = sum of resistance of each component (R^total = R^1 + R^2)

40
Q

Explain resistance in a parallel circuit:

A

More resistors, lower resistance. Total resistance of 2 resistors is less than resistance of smallest individual resistor

41
Q

What is the equation for charge?

A

Charge = current x time (Q = I x T)- QUIT

42
Q

What is the equation for potential difference?

A

p.d. = current x resistance (V = I x R) - Very Important Rabbit

43
Q

What is the equation for power?

A

Power = p.d. x current (P = I x V) - Penguins In Vegas

44
Q

What is the equation for energy transferred?

A

Energy transferred = power x time (E = P x T)

45
Q

What is electric current?

A

Flow of electric charge

46
Q

What is resistance caused by?

A

Anything which opposes the flow of electric charge

47
Q

What is charge?

A

Anything charged which is able to move within a circuit - electrons or ions

48
Q

What is a series circuit?

A

A circuit with only one route for charge to take

49
Q

What is a parallel circuit?

A

A circuit with more than one route for charge to take

50
Q

Describe the V/I graph of a filament lamp:

A

Resistance is not constant - as temp increases, resistance increases as ions vibrate more increasing collisions with electrons

51
Q

Describe the V/I graph of a fixed resistor:

A

Resistance is constant. Current and p.d. are directly proportional

52
Q

Describe the V/I graph of a diode/LED:

A

Current flows one-way. High resistance in reverse direction

53
Q

What is the function of a step-up transformer?

A

Increases p.d. for transmisson across power cables - less current, less heat lost

54
Q

What is the function of a step-down transformer?

A

Reduces the p.d. from the cables to 230V for use by consumers

55
Q

What power supply does batteries/cells use?

A

d.c. supply

56
Q

Where do electric fields exist?

A

Around all objects

57
Q

Electric fields - what does it mean if field lines are closer together?

A

Pulling force is stronger

58
Q

Where do field lines point?

A

Positive to negative charge

59
Q

What is the equation for density?

A

Density = mass (kg) / volume (m^3)

60
Q

What is density?

A

The mass of a substance per unit volume

61
Q

Are smaller objects more/less dense?

A

More dense

62
Q

What happens when 2 insulators are rubbed together?

A

They become charged

63
Q

What does friction force cause?

A

Electrons to be transferred between insulators

64
Q

Is the total no. of protons/electrons constant or alternating?

A

Constant

65
Q

Do oppositely charged objects attract/repel?

A

Attract

66
Q

Do objects with the same charge attract/repel?

A

Repel

67
Q

What is charging by induction?

A

When a negative object is moved towards a negative object, electrons are repelled to the other side - closest surface becomes positively charged. Works same other way, leaving opposite surface negatively charged

GCSE Revision Flashcards (21 decks)

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