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GCSE Physics 🪐 > Light And The Electromagnetic Spectrum > Flashcards

Light And The Electromagnetic Spectrum Flashcards

1
Q

What are the two types of lens?

A
  1. Convex
  2. Concave
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2
Q

What are convex lenses used for?

A

Correcting long sight

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3
Q

What are concave lenses used for?

A

Correcting short sight

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4
Q

What do concave lenses do?

A

Diverges the rays

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5
Q

What is the symbol for concave lenses?

A

¥
I

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6
Q

What do convex lenses do?

A

Converges the rays

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7
Q

What do convex lens look like?

A

<————->

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8
Q

What is the focal point?

A

The point where the light seems to have come from

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9
Q

What is the focal length?

A

Distance between the centre of the lens and the focal point

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10
Q

The more powerful the lens…

A

The shorter the focal length

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11
Q

Powerful lenses tend to be…

A

More curved

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12
Q

What are the 3 steps for ray diagram construction?

A
  1. Parallel ray
  2. Central ray
  3. Focal ray
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13
Q

What 3 things do you need to decide on ray diagrams?

A
  1. Orientation (inverted or upright)
  2. Real or virtual
  3. Size compared to object (magnified or diminished)
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14
Q

How do you identify real images?

A

Can be projected on a screen, virtual images cannot be

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15
Q

Problem with short sight? How’s it fixed?

A

Eyeball is too long, too powerful lens, image focussed before retina
Concave

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16
Q

Problem with long sight? How’s it fixed?

A

Eyeball too short, too weak lens, image focussed behind retina
Convex lens

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17
Q

How do we see?

A

Light from luminous objects reflects off objects into our eyes

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18
Q

What can happen to light?

A

Refracted
Reflected
Transmitted
Absorbed

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19
Q

What is white light made up of?

A

A spectrum of all the colours of the rainbow

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20
Q

What is needed to investigate white light?

A

Prism
Raybox

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21
Q

What are the primary colours of light?

A

Red
Green
Blue

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22
Q

What are the secondary colours of light?

A

Cyan
Yellow
Magenta

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23
Q

Why is light in a spectrum?

A

The different colours of light have different wavelengths, so they are refracted by different amounts

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24
Q

What colour is refracted the most and why?

A

Violet
Shorter wavelength

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25
Q

What colour is refracted the least and why?

A

Red
Longer wavelength

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26
Q

What do coloured objects do?

A

Absorb all of the colours of the spectrum except the colour of the object itself which it reflects

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27
Q

Why are white objects white?

A

Reflect all colours

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28
Q

Why are black objects black?

A

Absorb all colours

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29
Q

What do coloured filters do?

A

Absorb all the colours of the spectrum except the colour of the filter itself which they transmit

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30
Q

What are all em waves?

A

Transverse

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31
Q

What do all em waves travel at?

A

The speed of light

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32
Q

What can all em waves travel through?

A

Vacuum (space)

33
Q

What are the waves on the em spectrum?

A

Radio, microwave, infrared, visible light, ultraviolet, X-ray, gamma rays

34
Q

What is the frequency of visible light?

A

8 x 1014 - 4 x 1014

35
Q

What is the wavelength of visible light?

A

370 nm- 740nm

36
Q

Radio - gamma
What happens to wavelength?

37
Q

Radio - gamma
What happens to frequency?

38
Q

Radio - gamma
What happens to frequency?

39
Q

Radio - gamma
What happens to energy?

40
Q

What are gamma rays used for?

A

Nuclear bombs

41
Q

What are X-rays used for?

A

Seeing bones

42
Q

What are ultraviolet rays used for?

A

Getting a sun tan

43
Q

What are infrared rays used for?

44
Q

What do microwaves do?

A

Cooking food

45
Q

What do radio waves get used for?

A

Listen to radio

46
Q

What is reflection?

A

The waves bounce off the material

47
Q

What is Law of Reflection?

A

Incident Angle = Reflection angle

48
Q

What are the different types of reflection?

A

Speculator
Diffuse

49
Q

What is specular reflection?

A

Mirror reflection for a smooth flat surface creating a clear image

50
Q

What is diffuse reflection?

A

Light hitting a rough surface so the incident ray is reflected at many angles rather than one resulting in an affected reflected image that still follows the laws of reflection but different parts of the rough surface are reflected at different angles.

51
Q

What happens in refraction?

A

If light enters a dense material, it bends towards the normal and vice Vera

52
Q

What is Total Internal Reflection?

A

Total internal reflection occurs when light attempts to leave a glass or Perspex block with an angle of incidence bigger than the critical angle. The ray is then reflected instead of refracted

53
Q

How do optical fibres work?

A

Total Internal Reflection allows light to be bent and travel along the fibre

54
Q

When are optical fibres used?

A

Endoscopes (looking inside the body)
Fibre Broadband Internet

55
Q

What are the 4 rules of ray diagrams?

A

Image is same size, same distance, same way up as object
Image is laterally inverted

56
Q

Where are real images produced?

A

Other side of the lens

57
Q

Where are virtual images produced?

A

Same side of the lens

58
Q

What are some dangers of radio waves?

59
Q

What are some dangers of microwaves?

A

Internal heating of body cells

60
Q

What are some dangers of infrared waves?

61
Q

What are some dangers of visible light waves?

A

Eye damage from bright lights

62
Q

What are some dangers of UV waves?

A

Damage to surface cells and eyes, skin cancer, premature ageing

63
Q

What are some dangers of X-rays and gamma waves?

A

Mutations or damage to cells, cancer

64
Q

What rays produce types of ionising radiation?

A

UV
X-rays
Gamma

65
Q

What is ionising radiation?

A

Add or remove electrons produced electrically charged ions

66
Q

What does ionising radiation do?

A

Damages DNA and cause cells to mutate, tumours and cancer

67
Q

Ionising radiation:
Gamma, X-rays,UV waves have shorter wavelengths so…

A

Higher frequency and energy and better penetration in skin from skin to whole body

68
Q

What objects emit IR radiation?

69
Q

What is IR radiation?

70
Q

What colour emits and absorbs IR radiation best?

71
Q

If something absorbs or emits at the same rate,

A

The temperature is constant

72
Q

What is the greenhouse effect?

A
  1. Solar radiation passes through earths atmosphere
  2. Most radiation is absorbed and heated up
  3. Some is reflected back into the atmosphere
  4. Some IR radiation is absorbed and reemitted in all directions by greenhouse gases
73
Q

What is the enhanced greenhouse effect?

A

More greenhouse gases= more scattering= increase in temperature as the rate absorbed is greater than rate emitted

74
Q

How are radio waves used for communication?

A

Produced by oscillations in electrical circuits
When absorbed by a conductor, an alternating current is made
Has the same frequency as radio waves
Information is coded into the wave before transmission which can then be decoded when the wave is received

75
Q

What does Long wave radio waves do around large objects?

76
Q

What happens to short wave radio?

A

Reflected by the ionosphere

77
Q

What do radio/Tv require?

A

A line of sight between transmission and receiving aerial

78
Q

Can microwaves pass easily through the atmosphere?

79
Q

How are waves used for imaging?

A

Sensor detects waves, sends digital info to computer, process it, displays as visual information

GCSE Physics 🪐 (4 decks)

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