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Flashcards in P1 - Energy For The Home Deck (80):
1

What is amplitude?

Displacement from rest position to crest of wave.

2

What is the wavelength?

Length of full cycle of wave (from crest to crest)

3

What is the frequency of a wave?

Number of complete cycles/oscillations passing a certain point per second.

4

What are the standard units (SI) in a wave equation?

Meters, seconds, m/s and hertz (Hz)

5

What is the law of reflection?

Angle of incidence = angle of reflection

6

What is heat a measure of?

Energy

7

What is temperature a measure of?

Hotness - measures average kinetic energy of particles.

8

What is specific latent heat?

Amount of energy needed to boil/melt 1kg of material without changing its temperature.

9

What is conduction?

Conduction of heat is process where vibrating particles pass on extra kinetic energy to neighbouring particles.

10

What is specific heat capacity?

Amount of energy needed to raise temperature of 1kg of substance by 1°C

11

What is convection?

Convection occurs when more energetic particles move from hotter region to cooler region - and take their energy with them.

12

What can conduction occur in?

Mainly solids - liquids and gases conduct heat more slowly.

13

What can convection occur in?

Liquids and gases

14

How is heat radiation different to convection and conduction?

It doesn't need a medium, so can occur in a vacuum.

15

How does infrared radiation cook food?

(Grills and toasters) heat is absorbed by surface and then energy is conducted or convected to more central parts.

16

How do microwaves cook food?

Penetrate 1cm into outer layer. Absorbed by water/fat molecules increasing their kinetic energy - conducted or convected to other parts of food.

17

How do you calculate payback time?

payback time = initial cost ÷ annual saving

18

What colours on a thermograph show hot areas?

White, yellow and red

19

What colours on a thermograph show cold areas?

Black, dark blue and purple

20

How does loft insulation save energy?

Fibreglass wool across loft floor reduces conduction through ceiling into roof space.

21

How does a hot water tank jacket save energy?

Reduces conduction

22

How does double glazing save energy?

2 layers of glass with air gap between reduces conduction

23

How do thick curtains save energy?

Reduces conduction and radiation through windows

24

How does draught-proofing save energy?

Strips of foam and plastic around doors and windows stop hot air going out - reducing convection

25

How do cavity walls and insulation save energy?

2 layers of bricks with a gap between them reduces conduction. Some energy still lost by convection. Insulating foam in gaps traps pockets of air - minimises convection.

26

What causes total internal reflection?

If angle of incidence is bigger than critical angle - each material has a different critical angle.

27

What determines the amount of diffraction?

Size of gap relative to wavelength. Narrower gap, or longer wavelength, more wave spreads out.

28

What happens if a gap is the same size as a wavelength?

Get a diffraction pattern of light and dark fringes

29

What are the EM waves in order from largest wavelength to smallest?

Radio waves, Microwaves, Infra Red, Visible light, Ultra Violet, X-rays, Gamma Rays.

30

What is ionisation?

Where an atom or molecule either loses or gains electrons - can be dangerous.

31

What is special about the waves in a laser?

All waves are same wavelength and frequency (makes the light monochromatic). All waves in phase, increasing amplitude - coherent. Have low divergence; beam is narrow and stays narrow at long distances.

32

Why are long wavelengths good at transferring information over long distances?

They don’t get absorbed by Earth's atmosphere as much as waves in middle of spectrum or those with high frequency.

33

How far away can long wave radio waves be received?

(wavelength = 1-10km) can be transmitted from one place and received halfway around the world - diffract around Earth's curved surface.

34

How far away can short wave radio waves be received?

(wavelength about 10m - 100m) can be received at long distances from transmitter - reflection in ionosphere

35

What is diffraction?

Waves spread out at edges when passing through a gap/past an object.

36

What is refraction?

Wave changes speed due to a change in density. If wave hits a substance at an angle, it changes direction.

37

Displacement from rest position to crest of wave.

What is amplitude?

38

Length of full cycle of wave (from crest to crest)

What is the wavelength?

39

Number of complete cycles/oscillations passing a certain point per second.

What is the frequency of a wave?

40

Meters, seconds, m/s and hertz (Hz)

What are the standard units (SI) in a wave equation?

41

Angle of incidence = angle of reflection

What is the law of reflection?

42

Energy

What is heat a measure of?

43

Hotness - measures average kinetic energy of particles.

What is temperature a measure of?

44

Amount of energy needed to boil/melt 1kg of material without changing its temperature.

What is specific latent heat?

45

Conduction of heat is process where vibrating particles pass on extra kinetic energy to neighbouring particles.

What is conduction?

46

Amount of energy needed to raise temperature of 1kg of substance by 1°C

What is specific heat capacity?

47

Convection occurs when more energetic particles move from hotter region to cooler region - and take their energy with them.

What is convection?

48

Mainly solids - liquids and gases conduct heat more slowly.

What can conduction occur in?

49

Liquids and gases

What can convection occur in?

50

It doesn't need a medium, so can occur in a vacuum. Can only occur through transparent substances like air/glass/water. Amount of radiation emitted/absored depends on surface colour and texture.

How is heat radiation different to convection and conduction?

51

Like in grills and toasters heat is absorbed by surface and then energy is conducted or convected to more central parts.

How does infrared radiation cook food?

52

They penetrate 1cm into outer layer and absorbed by water/fat molecules increasing their kinetic energy - this is then conducted or convected to other parts of food.

How do microwaves cook food?

53

payback time = initial cost ÷ annual saving

How do you calculate payback time?

54

White, yellow and red

What colours on a thermograph show hot areas?

55

Black, dark blue and purple

What colours on a thermograph show cold areas?

56

Fibreglass wool laid across loft floor reduces conduction through ceiling into roof space.

How does loft insulation save energy?

57

Reduce conduction

How does a hot water tank jacket save energy?

58

2 layers of glass with air gap between reduces conduction

How does double glazing save energy?

59

Reduces conduction and radiation through windows

How do thick curtains save energy?

60

Strips of foam and plastic around doors and windows stop hot air going out - reducing convection

How does draught-proofing save energy?

61

2 layers of bricks with a gap between them reduces conduction but some energy still lost by convection. Insulating foam in gaps traps pockets of air to minimise convection.

How do cavity walls and insulation save energy?

62

If angle of incidence is bigger than critical angle - each material has a different critical angle.

What causes total internal reflection?

63

Size of gap relative to wavelength. Narrower gap, or longer wavelength, more wave spreads out.

What determines the amount of diffraction?

64

You can get a diffraction pattern or light and dark fringes

What happens if a gap is the same size as a wavelength?

65

Radio waves, Micro waves, Infra Red, Visible light, Ultra Violet, X rays, Gamma Rays.

What are the electromagnetic waves in order from largest wavelength to smallest?

66

Where an atom or molecule either loses or gains electrons - can be dangerous.

What is ionisation?

67

All waves are the same wavelength and frequency (makes the light monochromatic). All waves are in phase, increasing the amplitude - said to be coherent. Lasers have low divergence; beam is narrow and stays this way even at long distances.

What is special about the waves in a laser?

68

They don’t get absorbed by the Earth's atmosphere as much as waves in the middle of the spectrum or those with high frequency.

Why are long wavelengths good at transferring information over long distances?

69

(wavelength of 1-10km) can be transmitted from one place and received halfway around the world because they diffract around the Earth's curved surface.

How far away can long wave radio waves be received?

70

(wavelength about 10m - 100m) can be received at long distances from the transmitter because of reflection in the ionosphere

How far away can short wave radio waves be received?

71

When waves spread out at the edges when they pass through a gap or past an object.

What is diffraction?

72

When a wave changes speed due to a change in density. If the wave hits a substance at an angle, it changes direction.

What is refraction?

73

What is frequency measured in?

Hertz (Hz). 1Hz = 1 wave per second.

74

Hertz (Hz). 1Hz = 1 wave per second.

What is frequency measured in?

75

What scale is heat measured on?

Absolute scale (can't go lower than 0 because there is a limit to how slow particles can move)

76

Absolute scale (can't go lower than 0 because there is a limit to how slow particles can move)

What scale is heat measured on?

77

What can radiation occur through?

Can only occur through transparent substances like air/glass/water.

78

What determines the amount of radiation emitted?

Depends on surface colour and texture.

79

Can only occur through transparent substances like air/glass/water.

What can radiation occur through?

80

Depends on surface colour and texture.

What determines the amount of radiation emitted?