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Physics (Elliott) > Radiation and life > Flashcards

Flashcards in Radiation and life Deck (75):
1

The definition of Iodising radiation

radiation consisting of particles, X-rays, or gamma rays with sufficient energy to cause ionization in the medium through which it passes.

2

The definition of non Iodising radiation

Radiation with not enough energy to cause ionisation to the absorber

3

Materials are heated when they absorb

electromagnetic radiation of any type.

4

What speed does electromagnetic radiation travel at in a vacuum?

Electromagnetic radiation travels at 300 000km/s in a vacuum.

5

What are the 'packets' of energy in a beam of electromagnetic radiation called?

Photons

6

Why does ionising radiation cause chemical reactions when it is absorbed?

Ionising radiation causes chemical reactions because the radiation heats up the absorber.

7

Why are microwave ovens safe to use?

Microwaves are reflected by the metal sides and door screen

8

Some signals are made of a series of pulses which are just off or on. These are called...

digital signals

9

The amount of information needed to store information is measured in...

bytes

10

Signals can pick up random additions on their way to the receiver, making the quality poorer. What word is used for these 'random additions'?

noise

11

The rainbow pattern produced when white light shines through a prism is called the...

visible spectrum.

12

put these types of electro magnetic radiation in order of highest frequency to lowest:

visible light
microwaves
infrared radiation
x-rays
radio waves
gamma radiation
ultraviolet radiation

gamma radiation
x-rays
ultraviolet radiation
visible light
infrared radiation
microwaves
radio waves

13

Photons deliver different quantities of energy, with radi
o photons delivering the smallest amount, and gamma photons delivering the greatest amount of energy.


The photons deliver different quantities of energy, with radio photons delivering the smallest amount, and gamma photons delivering the greatest amount of energy.

A higher frequency of electromagnetic radiation means more energy is transferred by each photon.

If the photons have enough energy, they can break molecules into bits called ions. This is called ionisation. These types of radiation are called ionising radiation. This radiation can remove electrons from atoms in its path.

In the electromagnetic spectrum only the three types of radiation, which have the photons

14

The intensity of electromagnetic radiation is the energy arriving ... ... ........ ....... ... ......... .... ........ This depends on two things. What are they?

he intensity of electromagnetic radiation is the energy arriving at a square metre of surface each second.
It depends on the energy in each photon, and the number of photons arriving each second.

15

To have the same intensity, a beam of red light would need how many times as many photons as a beam of ultraviolet?

To have the same intensity, a beam of red light would need ten times as many photons as a beam of ultraviolet,

16

How do all forms of electromagnetic radiation deliver energy? The amount of heating depends on what?

All forms of electromagnetic radiation deliver energy. This will heat the material that absorbs the radiation. The amount of heating depends on the intensity of the radiation, and also the length of time the radiation is absorbed for.

17

How does Microwaves heat materials such as food ?

The molecules in the material absorb the energy delivered by the microwaves. This makes them vibrate faster, so the material heats up.

18

What are the ways that Information such as computer data can be transmitted?

Information such as computer data can be transmitted in a number of ways, including via waves and also analogue and digital signals. Infrared light, microwaves and radio waves are all used to transmit information such as computer data, telephone calls and TV signals.

19

Microwave radiation can be used to transmit signals to mobile phone calls through what means? Certain microwave radiation wavelengths pass through the Earth’s atmosphere and can be used to transmit information to and from what?

Microwave radiation can be used to transmit signals such as mobile phone calls. Microwave transmitters and receivers on buildings and masts communicate with the mobile telephones which are in their range.

Certain microwave radiation wavelengths pass through the Earth’s atmosphere and can be used to transmit information to and from satellites in orbit.

20

Radio waves are used for what ?

Radio waves

Radio waves are used to transmit television and radio programmes. Longer wavelength radio waves are reflected from an electrically charged layer of the upper atmosphere. This means they can reach receivers that are not in the line of sight because of the curvature of the Earth’s surface.

21

Why can digital information be more effective than analogue?

Before a sound or piece of information is transmitted, it is encoded in the transmitter in one of the ways described below - analogue or digital. The receiver must then decode the signal to produce a copy of the original information or sound.
Analogue signals vary continuously in amplitude, frequency or both.
Digital signals are a series of pulses with two states - on (shown by the symbol ‘1’) or off (shown by the symbol ‘0’). Digital signals carry more information per second than analogue signals and they maintain their quality better over long distances.

22

All signals become weaker as they travel long distances. They may also pick up ................ ............ ............ This is called ............, and it is heard as crackles and hiss on radio programmes. Noise may also cause an ............. ...................to drop, or slow down as the modem tries to compensate.

All signals become weaker as they travel long distances. They may also pick up random extra signals. This is called noise, and it is heard as crackles and hiss on radio programmes. Noise may also cause an internet connection to drop, or slow down as the modem tries to compensate.

23

Describe the effect of noise on Analogue signals



Noise adds extra random information to analogue signals. Each time the signal is amplified the noise is also amplified. Gradually, the signal becomes less and less like the original signal. Eventually, it may be impossible to make out the music in a radio broadcast from the background noise, for example.


24

What is the intensity of electromagnetic radiation ?

The intensity of electromagnetic radiation is the energy arriving at a square metre of surface each second

25

What are the different types of photons?


radio photons and gamma photons

26

What are photons?

Photons deliver different quantities of energy,

27

Photons deliver different quantities of energy, which give the smallers and which the greatest?

Photons deliver different quantities of energy - radio photons deliver the smallest amount, and gamma photons deliver the greatest amount of energy.

28

What does a higher frequency of electromagnetic radiation mean?

A higher frequency of electromagnetic radiation means more energy is transferred by each photon.

29

What is ionisation?

If the photons have enough energy, they can break molecules into bits called ions. This is called ionisation.

30

What is ionising radiation?

This radiation can remove electrons from atoms in its path.

31

Name a gas in the Earth’s atmosphere that absorbs infrared radiation.

carbon dioxide

32

describe the 4 steps of the greehouse effect

1.The Sun’s rays enter the Earth’s atmosphere
2.Heat is emitted back from the Earth’s surface at a lower principal frequency than that emitted by the Sun
3.Some heat passes back out into space
4.But some heat is absorbed by carbon dioxide, a greenhouse gas, and becomes trapped within the Earth’s atmosphere. The Earth becomes hotter.

33

Any process can be thought of in terms of................that may affect an .............
in global warming, one factor is the amount of carbon dioxide in the atmosphere. The outcome is the mean temperature of the atmosphere.

Any process can be thought of in terms of factors that may affect an outcome.

34

in global warming, name one factor and the outcome

Any process can be thought of in terms of factors that may affect an outcome.
in global warming, one factor is the amount of carbon dioxide in the atmosphere. The outcome is the mean temperature of the atmosphere.

35

To establish a correlation between a factor and an outcome, what is needed ?

Convincing evidence - This usually means that enough data must be collected, and that different samples should match

36

A correlation between a factor and an outcome does not mean that the factor causes the outcome. They could both be caused by some other factor. Give an example regarding children with bigger feet.

For example: Children with bigger feet (factor) are, on average, better readers (outcome).

There is another factor which affects both of these things: age. Older children usually have bigger feet, and older children are usually better readers!



37


Radiation that is not absorbed by the atmosphere does what?



Radiation that is not absorbed by the atmosphere reaches the Earth's surface and warms it, leading to the greenhouse effect.

38

The atmosphere transmits microwaves, and these can be used to do what?

The atmosphere transmits microwaves, and these can be used to communicate with satellites.

39

Any radiation absorbed by living cells can damage them by heating them. However, why are ionising radiations more likely to damage living cells?

This is because photons of ionising radiation deliver much more energy. They can easily kill cells, and can also cause cancer by damaging the DNA in the nucleus of a cell. This is because photons of ionising radiation deliver much more energy.

40

They are not ionising, and so cannot cause cancer in the way that ultraviolet, X-rays or gamma rays do.

They are not ionising, and so cannot cause cancer in the way that ultraviolet, X-rays or gamma rays do.

41

Why can microwaves not escape from the oven?

The microwaves cannot escape from the oven, because the metal case and the metal grid on the door reflect microwaves back into the oven

42

One health risk which is definitely present in our environment is ultraviolet, in sunlight. Not much of the ultraviolet reaching the Earth gets to us, - why?

One health risk which is definitely present in our environment is ultraviolet, in sunlight. Not much of the ultraviolet reaching the Earth gets to us, because the ozone layer high up in the atmosphere absorbs most of it. In the summer, it is wise to use sunscreens and clothing to absorb ultraviolet, and prevent it reaching the sensitive cells of the skin.

43

How does the ozone layer absorb ultraviolet ? Is this reversible?

The ozone layer absorbs ultraviolet because ultraviolet ionises the ozone, which then changes to oxygen. This chemical change is reversible, and the oxygen changes back to ozone.

44

What are the harmful affects of Chemicals used in aerosol spray cans and fridges ?

Chemicals used in aerosol spray cans and fridges gradually made their way up to the ozone layer when released into the atmosphere, and removed some of it. This has increased the intensity of the ultraviolet radiation reaching the Earth

45

What are the risks and benefits of ultraviolet ?

some ultraviolet is good for you, as it produces vitamin D in the skin

46

A higher frequency of electromagnetic radiation means what?

A higher frequency of electromagnetic radiation means more energy is transferred by each photon.

47

What is ionisation?

If the photons have enough energy, they can break molecules into bits called ions. This is called ionisation. These types of radiation are called ionising radiation. This radiation can remove electrons from atoms in its path.

In the electromagnetic spectrum only the three types of radiation, which have the photons

48

What has happened in the last 200 hundred years to the carbon cycle?

For thousands of years, the processes in the carbon cycle were constant, so the percentage of carbon dioxide in the atmosphere did not change. Over the past 200 years, the percentage of carbon dioxide in the atmosphere has increased steadily because humans are:
burning more and more fossil fuels as energy sources
burning large areas of forests to clear land, which means that there is less photosynthesis removing C02

49

how is Infrared light transmitted?

Information such as computer data and telephone calls can be converted into infrared signals and transmitted by optical fibres.

50

What is the advantages of optical fibre?

Optical fibres are able to carry more information than an ordinary cable of the same thickness. In addition the signals they carry do not weaken so much over long distances.

51

how do Television remote controls work?

Television remote controls use infrared light to transmit coded signals to the television set in order to, for example, change channels or adjust the volume.

52

An important advantage of digital signals over analogue signals as regards noise is what?

An important advantage of digital signals over analogue signals is that if the original signal has been affected by noise it can be recovered more easily. In analogue signals, when the signal is amplified to return to its original height, noise gets amplified as well.

53

name some other greenhouse gases?

Water vapour and methane

54

Why is methane effective?

Even though methane is present in trace (tiny) amounts only, it is a very efficient absorber of infrared.

55

A beam of microwaves would need how many times as many photons to be as intense as a beam of ultraviolet?

a beam of microwaves would need a million times as many.

56

Global warming could cause what?


Global warming could cause:
climate change
extreme weather conditions in some areas.

57

what provides evidence to support the view about global warming?

One piece of evidence that supports the view of scientists who blame human activities for global warming has been provided by 'supercomputers'. Computer generated climate models, based on different amounts of carbon dioxide in the atmosphere, produce the same changes as have been observed in the real world.

58

What could cause rising sea levels and the flooding of low-lying land?

Melting polar ice, and the thermal expansion of sea water, could cause rising sea levels and the flooding of low-lying land.

59

Extreme weather events become more likely due to what?

Extreme weather events become more likely due to increased convection accompanied by more water vapour being present in the hotter atmosphere.

60

Describe one piece of evidence that supports the view of scientists who blame human activities for global warming ?

One piece of evidence that supports the view of scientists who blame human activities for global warming has been provided by 'supercomputers'. Computer generated climate models, based on different amounts of carbon dioxide in the atmosphere, produce the same changes as have been observed in the real world.

61

What sort of questions do you need to ask when looking at graphs to establish correlation and cause?

consider these questions:
are the changes reported significantly large?
are they properly matched in terms of the times over which they are reported?
do these two graphs match well enough?





62

The ideas of correlation and cause are illustrated with the evidence for global warming.
How?

To investigate the relationship between a factor and an outcome, it is important to control all other factors that may affect the outcome.

Other factors affecting global warming

Another factor that may affect the mean temperature of the atmosphere is the amount of energy given out by the Sun. Most scientists agree that this has not changed in the past 200 years

There are some scientists who agree that global warming is taking place, but do not agree that carbon dioxide levels are to blame.

Once experiments have shown that there is a definite correlation between a factor and an outcome, it is still not enough to prove that the factor causes the outcome.

For this to be proven, there must be some scientific explanation of how the relationship can happen.
for carbon dioxide and global warming, the explanation is that carbon dioxide is a greenhouse gas. It absorbs infrared given off by the warm Earth, and this infrared cannot then escape into space. This keeps the Earth warmer than it would be if the carbon dioxide did not absorb so much infrared.

63

Information such as computer data and telephone calls can be converted into infrared signals and transmitted by by what

optical fibres. .

64

How does a Longer wavelength radio work?

Longer wavelength radio waves are reflected from an electrically charged layer of the upper atmosphere. This means they can reach receivers that are not in the line of sight because of the curvature of the Earth’s surface.

65

describe the effect of noise on Digital signals

Noise also adds extra random information to digital signals. However, this noise is usually lower in amplitude than the 'on' states of the digital signal. As a result, the electronics in the amplifiers can ignore the noise and it does not get passed along. This means that the quality of the signal is maintained. This is one reason why television and radio broadcasters are gradually changing from analogue to digital transmissions.

66

What are the advantages of digital?

They can also squeeze in more programmes because digital signals can carry more information per second than analogue signals. Another advantage of digital signals is that information can be stored and processed by computers.

67

Does the atmosphere absorb all radiation?





Some radiation of the electromagnetic spectrum is absorbed by the atmosphere, but some is transmitted.

68

which waves pass through the atmosphere?

Light, some infrared, some ultraviolet, and microwaves, pass through the atmosphere and reaches the Earth’s surface.

69

Which do not reach the earth's surface?

Gamma rays, X-rays, most of the ultraviolet and some of the infrared are absorbed by the atmosphere and do not reach the Earth’s surface.

70


what is the greenhouse effect?


Infrared from the Sun reaches the Earth’s surface and warms it.

The warm Earth emits some infrared radiation, and some of this is absorbed by gases in the atmosphere. This is called the greenhouse effect. If there was no greenhouse effect, the Earth would be too cold for life as we know it.

71

why is Photosynthesis?

Light from the Sun reaching the Earth’s surface provides the energy for plants to produce food by photosynthesis.

Photosynthesis replaces carbon dioxide in the atmosphere with oxygen. This reverses the process of respiration.

72

what are the risks from ultraviolet?

Some radiation, such as ultraviolet, exposes our skin to harmful rays and puts us at risk of developing skin cancer.

73

why has the percentage of carbon dioxide changed?


For thousands of years, the processes in the carbon cycle were constant, so the percentage of carbon dioxide in the atmosphere did not change. Over the past 200 years, the percentage of carbon dioxide in the atmosphere has increased steadily because humans are:
burning more and more fossil fuels as energy sources
burning large areas of forests to clear land, which means that there is less photosynthesis removing C02

74

What is the scientific argument about global warming?

There are some scientists who agree that global warming is taking place, but do not agree that carbon dioxide levels are to blame.

Once experiments have shown that there is a definite correlation between a factor and an outcome, it is still not enough to prove that the factor causes the outcome.

For this to be proven, there must be some scientific explanation of how the relationship can happen.
for carbon dioxide and global warming, the explanation is that carbon dioxide is a greenhouse gas. It absorbs infrared given off by the warm Earth, and this infrared cannot then escape into space. This keeps the Earth warmer than it would be if the carbon dioxide did not absorb so much infrared.

75

To investigate the relationship between a factor and an outcome, it is important to do what?

To investigate the relationship between a factor and an outcome, it is important to control all other factors that may affect the outcome.