CHAPTER 13 Flashcards
(97 cards)
1
Q
Why do different types of each wave have different effects
A
the energy they transfer depends on the wavelength of the waves
2
Q
what are the 7 waves
A
radio waves microwaves infrared visible light ultraviolet x-rays gamma rays
3
Q
wavelength of radio waves
A
between 1m and 1 x 10^4
4
Q
what type of waves are electromagnetic waves
A
transverse
5
Q
what do em waves dp
A
transfer energy from a source to an absorber
6
Q
wavelength of microwaves
A
10^-2 metres
7
Q
wavelength of infrared
A
10^-5 metres
8
Q
wavelength of visible light
A
10^-7 metres
9
Q
wavelength of ultraviolet
A
10^-8 metres
10
Q
wavelength or x rays
A
10^-10 metres
11
Q
wavelength of gamma rays
A
10^-15 metres
12
Q
what happens to the wavelength as you go down the spectrum
A
decreases
13
Q
what happens to the frequency as you go down the spectrum
A
increases
14
Q
why is there such a range of wavelengths in the em spectrum
A
the waves are generated by a variety of changes in atoms and atomic nuclei
15
Q
how fast do all em waves travel in a vacuum or in space
A
3x10^8 metres/second
16
Q
equation of wave speed
A
wavespeed m/s = frequency Hz x wavelength m
17
Q
what is white light
A
light that comes from the sun and ordinary lamps
18
Q
which colour has the longest wavelength
A
red
19
Q
which colour has the shortest wavelength
A
violet
20
Q
what do all objects emit
A
infrared radiation
21
Q
what happens to the amount of infrared radiation as the object gets hotter
A
it increases
22
Q
why is infrared radiation so damaging
A
it heats up cells to damage or kill them
23
Q
why is infrared used in optical fibres
A
it is absorbed by the glass fibres less than visible light
24
Q
why are microwaves used in satellite tv and communications
A
they can pass through earths atmosphere easily to reach satellites and carry mobile phone signals
25
why are are microwaves used in ovens
they penetrate food and are absorbed by the water molecules transferring their energy and heating it
26
how are microwaves used in satellites
they are sent out into space by a transmitter
the satellite picks up the signal and transmits it back to earth in a different direction where it is received by a satellite dish on the ground
27
why and how Is infrared used in tv remote controls
they are easily produced and received the controller sends out a series of infrared pulses
28
how do infrared cameras work
they detect infrared radiation and convert it to an electrical signal which is displayed on a screen
29
how do infrared heaters work
a wire emits infrared radiation it is absorbed by the objects in the room
energy is transferred by the infrared waves to their thermal energy stores and they heat up
30
uses of microwaves 2
communications
| heating food
31
properties of microwaves 3
absorbed by water molecules
can travel long distances
usually not harmful
32
uses of infrared3
remote controls
heating
thermal imaging
33
properties of infrared 2
easy and cheap to produce with not much power can be felt but not seen
34
uses of radio waves 3
mobile phones
radios
tvs
35
properties of radio waves
can travel long distances
low energy
normall not harmful
36
why can micro and radio waves be dangerous
they can penetrate and heat the body
37
what are the four carrier waves
radio waves
infrared
visible light
microwaves
38
what are carrier waves
used to carry a signal
39
properties shorter wavelength radio waves 2
carry more information
| smaller range
40
what are fibre optics and how do they work
they are small glass fibres that transmits signals carried by visible light or infrared radiation the light rays are reflected and cant escape the fibre
41
benefits of fibre optic over radio/microwaves
they can travel between the satellite and the ground they dont spread out so dont weaken as much as radio waves do
42
why are radio waves with short wavelengths used for tv broadcasting masts
they carry more information
43
why can long wave radio wavelengths be transmitted and received around the world
the long wavelengths diffract around the curved surfaced
| of the earth
44
why can short wave radio wave wavelengths be transmitted and received around the world
they are reflected from the ionosphere so zigzag around the world to their destination
45
what is the ionosphere
an electrically charged layer in the earths upper atmosphere
46
how does bluetooth work
it uses short wave radio wavelengths to send data over short distances
47
what are electromagnetic waves made from
oscillating electric and magnetic fields
48
what are alternating currents made from
oscillation charges
49
what is produced when alternating currents oscillates
electric and magnetic fields
50
why do microwaves heat food faster than normal ovens
they waves penetrate unto the food and are directly absorbed
51
why dont ovens absorb microwaves
they dont contain water molecules
52
uses of infrared radiation 3
remote control
night vision
heating
53
properties of infrared
easy and cheap to produce can be felt not seen
54
uses of visible light 3
seeing
lighting
signalling
55
properties of visible light 2
different colours can reflect and refract
56
uses of ultraviolet 2
sun beds
| security marking
57
properties of ultraviolet 3
can be harmful in large doses
| can be seen in insects
58
uses of x rays 2
seeing inside body luggage scanners
59
properties of x rays 3
can penetrate thin materials
blocked by dense materials like bones
harmful
60
uses of gamma rays 2
treat cancer cells
| kill bacteria
61
what is fluorescence
when certain chemicals absorb ultraviolet rays and emit visible light
62
why are ultraviolet waves harmful to human eyes
they carry more energy than visible light
63
difference between x rays and gamma rays
x rays are produced when electrons moving at high speeds are stopped gamma rays are produced by unstable nuclei releasing electrons
64
what is ionisation
when x rays or gamma rays knock electrons out of an atom making it charged
65
why is ionising radiation so dangerous
it can ionise and damage healthy body cells
66
why are x and gamma rays used in radiotherapy
they can kill living cells
67
why are gamma rays used in tracers
the gamma rays pass out of the body and can be detected so the source is tracked
68
what is the wavelength of an x ray the same as
the diameter of an atom
69
what is radiation dose
a measure of the damage done to a persons bod y by ionising radiation
70
what does the radiation dose depend on 3
the type of radiation used
how long the person is exposed to it
the energy the person absorbs from the radiation
71
what is radiation dose measured in
sieverts
72
how are x rays produced
when fast moving electrons hit a target in an x ray tube
73
what can high doses of radiation cause
killing live cells
74
what can low doses of radiation cause
gene mutation and cancerous growths
75
2 natural sources of ionising radiation
cosmic radiation from space
| radon gas from underground
76
how many millisieverts are in a sievert
1000
77
how are x rays used to destroy tumours
thick plates between x ray tubes and body stops rays from damaging healthy cells gaps in the plates allow rays to reach and destroy tumour
78
what is the wavelength of an x ray used for imaging like compared to one used for destroying cancerous tumour
they dont carry as much energy
79
process x ray imaging
x ray are directed at the body they pass through soft tissues but are absorbed by denser materials
bones appear white because this is where less x rays pass through. a ccd converts x rays to light to produce an image
80
what is a ccd and what does it do
charge coupled device
converts x rays into light
light rays create an electronic signal which is sent to a computer to create a visible image
81
use of lead plates in x rays and why
placed between the patient and the tube to stop rays reaching other body parts
lead is a good absorber of x rays
82
process of viewing internal organs
patient is given a barium, meal
barium absorbs x rays like bones
this shows where blockages are on a radiograph
83
what is a contrast medium
a material that absorbs x rays easily
84
what does the frequency of a wave determine
the higher the frequency the more energy transferred
85
consequences of too much uv radiation 4
sunburn
premature skin ageing
blindness
increased risk of skin cancer
86
what is radiation dose
a measure of the risk of harm from the body being exposed to radiation
87
what happens when an object that is hotter than its surroundings cools down
it emits more infrared radiation than it absorbs
88
what do objects that are at a constant temperature do
emit ir radiaron at the same rate they are absorbing
89
what is a perfect black bodyq
something that absorbs all radiaiton that hits it
90
why does the temperature of the earth increase in the day
more infrared radiation is absorbs and less is emitted
91
why does the temperature of the earth decrease at night
less radiation is being absorbs than emitted
92
what happens to the wavelengths emitted an when the temperature of n object increases
the intensity increases so the peal wavelength decreases
93
what are the oscillations like on a transverse wave
they oscillate perpendicularly to the direction pf energy transfer
94
examples of transverse waves 2
electromagnetic waves
| ripples on water
95
examples of longitudinal waves 2
sound waves in air shock waves
| seismic waves
96
what are the oscillations like on a longitudinal wave
parallel to the direction of energy transfer
97
how does a microphone work
alternating currents produce oscillation em waves the frueqnecy of the wave and current are equal. em waves travel to transmitter audio signal supplied to transmitter modulates carries waves alternating current causes transmitter aerial to emit radio waves carrying the signal waves received aerial oscillation cause receiver to oscillate at the same frequency receiver separates audio signal from carrier waves audio signal supplied to speaker sound waves similar to those in radio station are emitted
