P2 - Radiation and Life Flashcards

1
Q

What is the electromagnetic spectrum?

A

A family of seven radiations, including visible light

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2
Q

What does a beam of electromagnetic radiation contain?

A

‘Packets’ of energy called photons

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3
Q

Complete the sentence:

The higher the frequency of an electromagnetic radiation…

A

…the more energy is transferred by each photon

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4
Q

All electromagnetic radiation travels at the same finite speed of what?

A

300,000km/s through space (a vaccum)

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5
Q

Name 3 high energy photons, in order from lowest to highest.

A

Ultraviolet rays, x-rays, gamma rays

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6
Q

Name 3 low-energy photons, in order from lowest to highest.

A

Radio waves, microwaves, infrared

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7
Q

Name all 7 types of electromagnetic radiation in order from lowest energy photons to highest.

A

Radio waves, microwaves, infrared rays, visible light, ultraviolet rays, x-rays, gamma rays

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8
Q

The general model of radiation shows how energy travels from a ______ that _____ radiation, to a _______ that ____ radiation.

A
  • Source
  • Emits
  • Detector
  • Absorbs
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9
Q

On the journey from _______ to _______, materials can _______, ____ or _________ radiation.

A
  • Emitter
  • Detector
  • Transmit
  • Reflect
  • Absorb
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10
Q

Give an example of how on the journey from emitter to detector, materials can transmit, reflect or absorb radiation.

A

Clouds absorb and reflect the Sun’s energy, so on a cloudy day, we receive less light than on a clearer day.

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11
Q

Give an example of a) an emitter and b) its detector for radio waves.

A

a) TV transmitter

b) TV aerial

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12
Q

Give an example of a) an emitter and b) its detector for microwaves.

A

a) Mobile phone mast

b) Mobile phone

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13
Q

Give an example of a) an emitter and b) its detector for infrared waves.

A

a) Remote control

b) Television

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14
Q

Give an example of a) an emitter and b) its detector for light.

A

a) The Sun

b) The eye

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15
Q

Give an example of a) an emitter and b) its detector for ultraviolet rays.

A

a) Ultraviolet lamp

b) The skin

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16
Q

Give an example of a) an emitter and b) its detector for x-rays.

A

a) X-ray machine

b) Photographic plate

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17
Q

Give an example of a) an emitter and b) its detector for gamma rays.

A

a) Some stars (e.g. supernova)

b) Gamma ray telescope

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18
Q

What is the intensity of electromagnetic radiation?

A

The energy arriving at a square metre of surface per second

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19
Q

What does intensity of electromagnetic radiation depend on?

A

The number of photons delivered per second and the amount of energy each packet contains, i.e. the photon energy

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20
Q

a) Does the intensity of a beam increase or decrease with distance?
b) What does this mean?

A

a) The intensity of a beam decreases with distance

b) The further from a source you are, the lower the intensity.

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21
Q

When a material absorbs radiation, what is created?

A

Heat

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22
Q

When a material absorbs radiation, heat is created. What 2 things does the amount of heat created depend on?

A
  • The intensity of the radiation beam

- The duration of the exposure

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23
Q

a) The decrease in the intensity of radiation with distance is due to what 3 factors? (HT)
b) Why would these factors combine? (HT)
c) What does this result in? (HT)

A

a) - Photons spread out as they travel
- Some photons are absorbed by particles in the substances they pass through
- Some photons are reflected and scattered by other particles.
b) To reduce the number of photons arriving per second at a detector
c) A lower measured intensity

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24
Q

What is ionising radiation?

A

Electromagnetic radiation with a high photon energy

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25
Q

What can ionising radiation do?

A

Break molecules into bits called ions

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26
Q

When molecules are broken into bits by ionising radiation, what are the resultant ‘bits’ called?

A

Ions

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27
Q

Give some examples of ionising radiation.

A
  • Ultraviolet radiation
  • X-rays
  • Gamma rays
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28
Q

Are ions unreactive or very reactive? (HT)

A

Very reactive

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29
Q

Ions are very reactive which means? (HT)

A

They can easily take part in other chemical reactions

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30
Q

Give 3 ways in which radiation damages living cells.

A
  • The heating effect can damage the skin, e.g. sunburn
  • Ionising radiation can age the skin. It can also mutate DNA, which can lead to cancer
  • Different amounts of exposure can cause different effects, e.g. high intensity ionising radiation can destroy cells, leading to radiation poisoning.
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31
Q

Give a way that heat radiation can damage the skin.

A

Sunburn

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32
Q

How do microwaves heat materials?

A

By causing the water particles to vibrate.

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33
Q

What could there be a health risk from with low intensity microwaves?

A

Of mobile phones and masts

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34
Q

Microwave ovens have a metal case and a wire screen in the door to do what?

A

Absorb ultraviolet radiation to help prevent skin cancer

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35
Q

Why do microwave ovens have a metal case and a wire screen in the door to absorb ultraviolet radiation?

A

To help prevent skin cancer

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36
Q

Give some examples of other physical barriers to protect people from different types of radiation.

A
  • X-ray technicians use lead screens
  • Sunscreens and clothing can absorb ultraviolet radiation to help prevent skin cancer
  • Nuclear reactors are encased in thick lead and concreate
37
Q

True or False?

Some radioactive materials emit ionising gamma radiation all the time.

A

True

38
Q

a) What must people going into areas of high radiation wear?
b) Why?
c) What else must they have?

A

a) A radiation suit
b) As a shield
c) Radiation dose monitor

39
Q

All objects emit electromagnetic radiation with a _________ _________ that increases with temperature.

A

Principal frequency

40
Q

All object emit electromagnetic radiation with a principal frequency that ________with temperature.

A

Increases

41
Q

Does photosynthesis compliment or counteract respiration?

A

Counteract

42
Q

How does photosynthesis counteract respiration?

A

It removes carbon dioxide and adds oxygen

43
Q

What is the ozone layer?

A

A thin layer of gas in the Earth’s upper atmosphere.

44
Q

What does the ozone layer absorb?

A

Some of the Sun’s ultraviolet radiation before it reaches Earth.

45
Q

What would happen without the ozone layer?

A

The amount of radiation reaching the Earth would be very harmful. Living organisms, especially animals, would suffer cell damage

46
Q

What does the energy from ultraviolet radiation cause? (HT)

A

Chemical changes in the upper atmosphere when it’s absorbed by the ozone layer. These

47
Q

The energy from ultraviolet radiation causes chemical changes in the upper atmosphere when it’s absorbed by the ozone layer. Are these changes reversible or irreversible? (HT)

A

These changes are reversible.

48
Q

Where does the Earth emit electromagnetic radiation to?

A

Space

49
Q

What is in the atmosphere that absorbs radiation, and keeps the earth warmer.

A

Gases in the atmosphere

50
Q

What is it known as when gases in the atmosphere absorb radiation, keeping the earth warmer?

A

The Greenhouse effect

51
Q

What is the Greenhouse effect?

A

When gases in the atmosphere absorb radiation, keeping the earth warmer.

52
Q

How much electromagnetic radiation emitted by the Sun does the atmosphere allow to pass through?

A

Only some

53
Q

Which greenhouse gas makes up a small amount of the Earth’s atmosphere?

A

Carbon dioxide.

54
Q

Other than carbon dioxide, name some greenhouse gases.

A
  • Water vapour

- Trace amounts of methane

55
Q

Does radiation emitted by the Earth have a lower or higher principal frequency than that emitted by the Sun? (HT)

A

Lower

56
Q

Is the carbon cycle an example of a balanced or an unbalanced system?

A

Balanced

57
Q

What does burning forests

a) release?
b) reduce?

A

a) Carbon

b) The number of plants removing CO[2] from the atmosphere

58
Q

What does burning fossil fuels release?

A

Carbon that was removed from the atmosphere millions of years ago and had been ‘locked up’ ever since

59
Q

For what reason have carbon dioxide levels in the atmosphere been steadily increasing?

A

Due to human activity, e.g. burning fossil fuels and deforestation

60
Q

What are decomposers?

A

Important microorganisms that break down dead material and release CO[2+]

61
Q

Why have carbon dioxide levels in the Earth’s atmosphere remained roughly constant for thousands of years?

A

Because it was constantly being recycled by plants and animals

62
Q

How can information (including sound) be transmitted?

A

Digitally

63
Q

What things can be transmitted digitally?

A

Information (including sound)

64
Q

How is information transmitted digitally?

A

The signal is converted into digital code that uses 0 and 1. This is then transmitted as pulses (a series of short bursts of waves). The pulses are decoded to produce a copy of the original sound wave or image.

65
Q

How are digital pulses read?

A
0 = no pulse
1 = pulse, i.e. on
66
Q

How are digital pulses produced?

A

By switching the electromagnetic carrier wave on and off

67
Q

What happens when digital signal is received?

A

The pulses are decoded to produce a copy of the original sound wave or image.

68
Q

What actually happens when analogue and digital signals become weaker as they travel?

A

Their amplitude becomes smaller

69
Q

Why might digital and analogue signals have to be amplified at selected intervals?

A

Because they become weaker as they travel, meaning their amplitude becomes smaller.

70
Q

What is the name given to the random variations that digital and analogue signals can pick up?

A

Noise

71
Q

What is the problem with noise?

A

It reduces the quality of sound

72
Q

What happens when a signal is amplified?

A

Any ‘noise’ which has been picked up is also amplified

73
Q

Do digital signals travel longer or shorter distances at a higher quality than analogue signals?

A

Longer

74
Q

Why do digital signals travel longer distances at a higher quality than analogue signals? (2 reasons)

A
  • Analogue signals can have many different values, so it’s hard to distinguish between noise and the original signal. This means that noise can’t be completely removed.
  • Digital signals only have 2 states, on (1) or off (0), so they can still be recognised despite any noise that’s picked up. This means that any interference can be removed.
75
Q

When digital signals carry noise, it’s clear which parts of the signal represent 1 and 0, which means what? (HT)

A

The signal can be regenerated without the noise.

76
Q

What is a ‘bit’?

A

One piece of information, represented as either 1 or 0.

77
Q

What is one byte equal to?

A

8 ‘bits’ of information.

78
Q

How is a ‘bit’ represented?

A

As either a 1 or a 0.

79
Q

In a digital mobile phone picture, what does each pixel need?

A

8 bits of information, or one byte (same thing).

80
Q

In a digital mobile phone picture, each pixel needs eight bits of information or one byte - the more pixels in the picture… (2 things)

A

…the more bytes of information there are

…the higher the quality of the picture

81
Q

a) Where is a digital picture stored on a mobile phone?

b) How is the amount of information stored measured?

A

a) On a memory card

b) In bytes

82
Q

What else can be stored in the form of bytes?

A

Digital music on CDs

83
Q

How is digital music stored on a CD in bytes?

A

There is a series of pits, each read by a laser as 1 (a bit), arranged in a spiral on the surface. In between are flat surfaces read as 0. The series of bits is then converted back into analogue form giving a high quality signal.

84
Q

Give 2 advantages of transmitting information using digital signals.

A
  • Information can be stored, e.g. on hard drive, CD, DVD, or memory stick
  • Information can be processed by computer, e.g. for spell checking, photo editing or music editing
85
Q

Explain 2 ways by which a computer can be used to process and store digital picture information.

A
  • Use of photo editing software to manipulate images

- Store on hard drive, CD, or memory stick

86
Q

Explain 2 ways by which a computer can be used to process and store music information in MP3/WAV format.

A
  • Remove noise, amplify and edit signals

- Store on hard drive, CD or memory stick

87
Q

Why is optic fibre useful when sending infrared and light radiation?

A

They can travel huge distances without becoming significantly weaker

88
Q

How is data, collected about the Earth’s changing temperature, used? (HT)

A

It is used with climate models to look for patterns in the possible causes of global warming.