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Physics 1, 2 + 3 > Physics 2: Radiation and life > Flashcards

Physics 2: Radiation and life Flashcards

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1
Q

Reflect

A

In the case of light, re-direction of the light wave, usually back to the point of origin from a shiny surface

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2
Q

Absorb

A

To take in energy from electromagnetic radiation; this is transferred to the particles of the material

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3
Q

Talk about how different coloured objects

A
  • Everything that you see reflects light.
  • Black objects don’t reflect much light, they mostly absorb it.
  • Shiny objects reflect most of the light that falls on them
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4
Q

Electromagnetic spectrum

A

Electromagnetic waves ordered according to wavelength and frequency - ranging from radio waves to gamma rays

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5
Q

transmitted

A

Radiation that parts through a material

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6
Q

What is part of the electromagnetic spectrum

A

Light

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7
Q

Vacuum

A

A space where there are no particles of any kind

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8
Q

How do waves transmit through a vacuum

A

At 300 000km/s

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9
Q

How does the energy of the wave and frequency relate

A

The energy of a wave in the spectrum increases with increasing frequency. Waves with higher frequencies carry more energy

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10
Q

How do electromagnetic waves are grouped in ranges of frequency

A 
Lowest energy 
Radio waves 
Microwaves 
Infrared 
Visible spectrum 
Ultra-violet 
X-Ray's 
Gamma rays 
Highest energy
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11
Q

How do electromagnetic waves transfer

A

Electromagnetic waves transfer energy in packets called photons

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12
Q

Electromagnetic radiation

A

energy transferred as electromagnetic waves

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13
Q

What is the relationship between energy in a photon and the frequency of an electromagnetic wave

A

The energy in a photon depends on The frequency of the wave. Increasing the frequency of an electromagnetic wave increases the energy of its photons

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14
Q

Give another source that produces electricity and how it works

A

Solar cells produce electricity. They work by absorbing electromagnetic radiation from the sun. The solar cell transfers energy to the electrical energy

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15
Q

Intensity

A

A measure of the power of a being of radiation

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16
Q

What does electromagnetic waves intensity depend on

A

The energy absorbed in each second from an electromagnetic wave depends on its intensity. This depends on:

  • The number of photons per second (intensity increases with the number of photons)
  • The energy transferred by each proton (intensity increases with energy)
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17
Q

How does the energy of a wave spread

A
  • The energy of the way is spread over and increasing area as it moves away from its source.
  • this means that the intensity of the wave decreases with increasing distance from its source
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18
Q

What are the units of intensity

A

The intensity of an electromagnetic wave is the energy transferred to each square metre of absorbing surface in each second. The units of intensity are therefore J/m2/s

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19
Q

Describe the relationship between the intensity of a wave in a vacuum and the square of its distance from its source

A
  • The intensity of a wave in a vacuum is inversely proportional to to the square of its distance from its source
  • if the wave is partially absorbed by the medium it is passing through, the intensity drops even more rapidly than an inverse square law
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20
Q

The charges of atoms, molecules, electrons and ions

A

Atoms and molecules have no overall electric charge. Electrons are negative they charged. Ions have either positive or negative charge

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21
Q

When do atoms or molecules become ionised

A

Atoms or molecules are ionise when they lose electrons

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22
Q

Ionising radiation

A

Electromagnetic radiation that has sufficient energy to ionise the material it is absorbed by

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23
Q

What part of the atom has enough energy to ionise atoms or molecules

A

The photons of an ionising radiation have enough energy to ionise atoms or molecules

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24
Q

Name the only ionising radiations in the electromagnetic spectrum

A

The only Ionising radiations in the electromagnetic spectrum are high energy ultraviolet, x-rays and gamma rays

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25
Q

X-rays

A

Ionising electromagnetic radiation

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26
Q

Gamma rays

A

Ionising high energy electromagnetic radiation from radioactive substances, harmful to human health

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27
Q

How does Ionisation of the molecule start

A

Ionisation of a molecule can start off a chemical reaction involving that molecule

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28
Q

Radioactive

A

A material that randomly emits Ionising radiation from its atomic nuclei

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29
Q

What can gamma rays pass through

A

Gamma rays pass easily through the human body

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30
Q

What can x-rays passed through

A

X-rays pass through muscle but are absorbed by bone

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31
Q

How are cells affected by gamma rays or x-rays

A

Cells are ionised and damaged when they absorb cameras or x-rays. The damage cells can either die or develop into cancer

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32
Q

Why are x-rays used for peoples bones or their luggage

A
  • physical barriers absorb some ionising radiation

* x-rays are absorbed by dense materials, so x-rays are used to make Shadow pictures of peoples bones or their luggage

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33
Q

Radiographer

A

Medical worker who takes and processes body images

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34
Q

What Do you radiographers do

A

Hospital workers such as radiographers are protected from ionising radiation by lead and Concrete screens

35
Q

Radiation

A

Energy transfer by electromagnetic waves or fast moving particles

36
Q

How does radiation heat things up

A
  • things which absorb radiation heat up

* cells which absorb radiation Are damaged if they get too hot

37
Q

How can we increase family energy transferred from radiation

A

• you can increase the thermal energy transferred from radiation by increasing its of exposure time and intensity

38
Q

Microwaves

A

Lecture magnetic waves similar to radio waves but with higher energy

39
Q

Which liquid is good at transferring energy in microwaves to thermal energy

A

Water molecules, as the water absorbs the microwaves they vibrate more and share this energy with other molecules around them

40
Q

How do you other substances other than water heat up by absorbing microwaves

A

Cells contain water so heat up when they absorb microwaves

41
Q

How do microwave ovens work

A
  • Microwave ovens can only be used to heat up food which contains water.
  • Microwaves reflect of the metal in the walls and door or are absorbed by them instead of escaping.
  • This protects people from the radiation
42
Q

Which waves do my mobile phone networks use

A

Mobile phone networks is low intensity my place. The heating effect of these microwaves is very small, but some people are concerned about health risks from the radiation

43
Q

What is the risk of cell damage from mobile phones

A
  • The risk of cell damage from mobile phones is measured by comparing cancer rates in large groups of people who do and do you not use mobile phones.
  • There is no evidence of harm from mobile phone use
44
Q

What type of radiation does sound like in town and how does it affect the body

A
  • sunlight contains ultraviolet radiation. Ultraviolet radiation causes sunburn and skin cancer
  • sunscreens uncloven protect people by absorbing ultraviolet radiation emitted by the sun
45
Q

Ozone

A

Gas found high in the atmosphere which absorbs ultraviolet rays from the sun. This protects living things on earth from some of the harmful effects of ultraviolet radiation

46
Q

What are the effects of increased exposure to ultraviolet radiation

A
  • Increased exposure to ultraviolet radiation increases the risk of developing skin cancer.
  • If the ozone layer thins by 1%, the rest of skin cancer increases by about 4%
  • ultraviolet radiation from the sun causes chemical changes to molecules in the ozone layer
47
Q

Describe the stages of the greenhouse effect

A
  • Radiation from the sun contains a range of frequencies. Only some of those frequencies pass through the atmosphere to the earth
  • The earth warms up when it absorbs radiation from the sun
  • The infrared radiation emitted by the earth makes it cool down. Radiation from the earth may pass into space, reflect off clouds or radiate it back from gases which absorb it
  • when the earths radiation name is absorbed back or reflected back, this keeps the earth warmer. We call this the greenhouse effect
48
Q

Atmosphere

A

Thin layer of gas surrounding a planet

49
Q

Principal frequency

A

The main frequency of electromagnetic radiation emitted by an object; hotter objects have higher principal frequencies

50
Q

Which has a higher frequency of radiation from the sun or earth

A

Radiation from the hot sun has higher frequency than radiation from the cold earth

51
Q

Describe the carbon cycle

A
  • carbon is found in all living things. It is currently being recycled through the carbon cycles
  • carbon dioxide in the atmosphereis found in very small amounts. It’s by plants through photosynthesis and release by living organisms as they rot (decompose) and respire
52
Q

Photosynthesis

A

Process carried out by green plants in which sunlight, carbon dioxide and water are to produce glucose and oxygen

53
Q

Respiration

A

Process occurring in living things where oxygen is used to release the energy in foods

54
Q

Greenhouse gases

A

Aigas such as carbon dioxide that reduces the amount of infrared radiation escaping into space, thereby contributing to global warming

55
Q

How was The level of carbon dioxide in the past

A

The level of carbon dioxide in the atmosphere has been steadied for thousands of years, because the rates of absorption and release of carbon dioxide is have been the same.

56
Q

Two reasons in the last 200 years the level of carbon outside is that the increased

A
  • The burning of fossil feels as an energy sources increase the rate of release
  • cutting down for it (deforestation) to clear land has increased the rate of absorption
57
Q

Fossil fuels

A

You such as coal, oil or natural gas formed millions of years ago from the plants and animals

58
Q

Deforestation

A

The large-scale removal of trees from forested areas for building farming

59
Q

How does the increase in temperature carbon dioxide correlate

A
  • The recent increase in the temperature of the Earth correlates with the rise in carbon dioxide levels in the ass atmosphere.
  • Many scientists believe that this correlation is caused by the carbon dioxide because it is a greenhouse gas
  • The greenhouse effect is slowly increasing the average temperature worldwide. This is called global warming.
60
Q

How does level warming affect nature

A

Able woman will have benefits, including: changes to crops which can grow in the region; flooding of low-lying land due to the rise of sealevel as the sea expands and glaciers melt

61
Q

Gases are responsible for the greenhouses effect

A

Various gases in the atmosphere responsible for the greenhouse effect:

  • water vapour has the most effect, because there’s so much of it
  • The small amount of carbon dioxide has an effect
  • methane is a strong absorber of infrared radiation, but there is very little of it
62
Q

How are the affects of global warming predicted

A

Scientists use computer models to predict the effects of global warming. The models are tested by seeing if they can use past data to predict today’s climate

63
Q

How did model suggests that the woman is out in more extreme weather events

A
  • increased water vapour in the hotter atmosphere

- increase convection in the atmosphere increasing windspeed

64
Q

Convection

A

Heat transfer in a liquid or gas, when particles in a warmer region gain energy and move into cooler regions, carrying this energy with them

65
Q

How can radio waves and microwaves carry radio and TV broadcast through the atmosphere

A

Radio waves and microwaves are not absorbed by air. This means that they can carry radio and TV programmes through the atmosphere

66
Q

infrared and light for electromagnetic waves for communication

A

Infrared and lights are not easily absorbed by glass of optical fibres. This means that they can be used for telephone and Internet communication

67
Q

How do radiowave is transfer information

A
  • Radio waves use a carrier wave to transfer information.

* this information is used to change the amplitude of frequency of the carrier, in a process called modulation

68
Q

Carrier wave

A

Magnetic wave on which signal is superimposed for transmission

69
Q

How is the information recovered from the carrier wave

A

Radio receiver demodulates The carrier wave to recover the information

70
Q

How does an analogue signal vary, give an example

A

And analogue signal where is continuously with any value. Sound isn’t example of an analogue signal

71
Q

How does modulation vary

A

Modulation which varies the amplitude of a radio Wave continuous makes analogue signals

72
Q

Digital signal

A

Transmitted information that can take only a small number of discrete values, usually just 1 and 0

73
Q

What are the properties of digital signal

A

A few digital signal has only a few values. The digital code for sending sound or pictures is only two values, called one and zero.

74
Q

How does analog signals vary

A

By contrast, analog signals are those which vary continuously

75
Q

How are analogue signals sent, describe the steps in which they do so

A

Analog signals, such as sound, can be sent by radiowave in a digital code:

1) The value of the signal is measured
2) The value is coded as a string of 1s and 0s
3) The 1s and 0s make a digital signal by pulsing the carrier wave on and off (where 0= no pulse and 1 = pulse)
4) The process is repeated many times a second

76
Q

How do radio receivers decode analogue signals

A

Radio receivers use the strings of 1s and 0s are in the digital signal to recover (the code) the original analog signal and produce a copy of it

77
Q

How can radio waves be affected

A
  • Radio waves can’t be affected by unwanted information or noise. Noise changes the amplitude of the carrier continuously.
  • noise always reduces the quality of the signal covered by an analogue receiver, because the original signal cannot be separated from the noise
78
Q

How is the way pulses separated from varying noise

A

The wave pulses which carry information can usually be separated from the continuously varying noise in a Digital receiver, so the quality of the signal is not affected

79
Q

What is digital information stored

A

Digital information is stored as bytes

80
Q

Byte

A

A measure of digital data consisting of eight binary digits

81
Q

Pixels

A

A tiny area (for example adopt all square) on the screen which conveys the data relating to a small part of the picture

82
Q

Properties of a binary digit

A
  • each binary digit can either be 1 or 0
  • The colour and brightness of each pixel is set by binary digits
  • increasing the number of binary digits for a picture increases the sharpness of the image
  • Digital information builds up sound from rapid series of values or samples the value of eight sample is set up by binary digits
  • increase in the number of binary digits for a sound increases its quality
83
Q

What is in advantage of using digital signals

A

And advantage of using digital signals is that they are easily stored in electronic memories so can be processed by computers

Physics 1, 2 + 3 (3 decks)

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