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KIRKCALDY HIGH SCHOOL
Physics Department
Waves and Radiation
Electromagnetic Spectrum
Question Booklet
Kirkcaldy High School
(collated by Anderson High School)
Radio and Television
Two equations which are useful in answering questions on waves are
v=fλ
λ
Where
v
f
λ
d
t
=
=
=
=
=
and
v= d
t
average speed in metres per second (m/s)
frequency in hertz (Hz)
wavelength in metres (m)
distance in metres (m)
time in seconds (s)
Helpful Hint
Radio and television waves are electromagnetic waves which
travel at a speed of 3 x 10 8 m/s (3 00 000 000 m/s)
through space.
Two more useful units are:
1 kHz
1 MHz
= 1 000 Hz
= 1 x 103 Hz
= 1 000 000 Hz = 1 x 106 Hz
1.
A radio wave has a wavelength of 9 540 m. What is the frequency
of this wave?
2.
Calculate the frequency of a radio wave which has a wavelength of
442 m.
3.
A radio wave with a frequency of 6 500 Hz would be called a very
low frequency radio wave (VLF). What is the wavelength of this
radio wave?
4.
The navy use long wavelength radio waves for telecommunication.
Calculate the frequency of a radio wave with a wavelength of
8600 m used by the navy to communicate at sea.
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Radio and Television
5.
Different radio stations use different frequencies of radio wave to
carry information from the radio transmitter to the radio receiver.
Radio frequencies used for sound broadcasting are often measured
in kilohertz (kHz) or megahertz (MHz).
Convert each of the following frequencies into hertz.
(a)
1 215 kHz
( d)
88 MHz
(b)
810 kHz
( e)
97·6 MHz
(c)
548 kHz
( f)
850 MHz.
6.
If you look in a newspaper or television magazine you will see
information on radio and TV programmes. The radio section usually
gives you the frequency of each radio station so that you can find
the programme that you want to listen to on the radio.
Below is a list of some radio stations you can tune into on medium
wave (MW).
(a)
(b)
(c)
Virgin Radio
Radio Scotland
Radio Forth
MW
MW
MW
1 215 kHz
810 kHz
1 548 kHz
Calculate the wavelength of each of these stations in metres.
7.
Many BBC radio programmes are broadcast on FM. FM broadcasts
provide good sound quality and suffer less interference than MW
broadcasts. FM broadcasts use very high frequency waves which
are measured in Megahertz (MHz)
Look at the list of frequencies for BBC broadcasts on FM.
Radio 1
Radio 2
Radio 3
Radio 4
Calculate the wavelength
8.
FM
97·6 MHz
FM
88 MHz
FM
92·4 MHz
FM
96·1 MHz
of each of these radio waves in metres.
Radio 5 Live broadcasts a news programme called ‘News Extra’ at
7.00 pm on MW 433 m.
Calculate the frequency of this broadcast
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Radio and Television
9.
Radio Scotland broadcasts programmes on both FM and MW.
Between 9pm and 10 pm a classical music programme called ‘The
Score’ is broadcast on FM (3·2 m ) only. At the same time on MW
(370·3 m) Gaelic programmes are broadcast.
(a)
(b)
10.
Calculate the frequency of the programme called ‘The Score’.
What frequency would you tune your radio to in order to
receive the MW programmes?
A television signal is sent in the same way as a radio signal. To
broadcast a television programme two radio carrier waves are
needed. One wave carries the picture information and one wave
carries the sound information.
BBC 1 use a 621·25 MHz radio wave to carry the sound signal and a
615·25 MHz radio wave to carry the picture signal.
Calculate the wavelength of each of these carrier waves.
11.
An Olympic athlete can run 100 m in 10 seconds. How far would a
radio wave travel in 10 seconds?
12.
How long would it take for a radio signal to travel from the
broadcasting station to a radio receiver 40 km away?
13.
How far could a radio wave travel in 3 minutes?
14.
A long distance lorry driver uses a CB radio to talk to a colleague
48 km away. How long does it take for the radio wave to travel this
distance?
15.
On 12 December 1901 Gugliemo Marconi sent the first radio
message across the Atlantic ocean. The message travelled a total
distance of 3 440 km between Cornwall in England and
Newfoundland in Canada.
How long did it take the radio message to travel between England
and Canada?
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Radio and Television
16.
Air traffic control sends a radio message to an aeroplane that is
preparing to land at Aberdeen airport. The plane is instructed to
descend to 1000 m.
The plane was 8 km from the control tower when it received the
instruction.
control tower
8 km
Calculate how long it took for the radio message to reach the
aeroplane.
17.
A police patrol car is called to the scene of a road traffic accident.
The police constables received the message sent from their police
station on the car radio. The message took 6·5 x10-5 seconds to
reach the car. Calculate how far the patrol car is from the station
when it receives the message.
18.
A Channel 4 programme is transmitted from an aerial outside
Inverness. A radio wave of frequency 645·25 MHz carries the
sound signal. The picture signal is carried by a radio wave of
frequency 639·25 MHz.
(a)
Calculate the wavelength of the radio wave carrying the
picture signal.
(b)
How long would it take for the sound signal to reach
Aberdeen which is 152 km from the transmitter?
(c)
How far would the picture signal travel in 8·5 x 10
seconds?
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Radio and Television
19.
Radio waves of different frequencies have different properties
and are used for different purposes.
Radio waves of frequency 30 Hz - 3 kHz are called extra low
frequency (ELF) and are used for communicating with submarines
which are moving in deep water.
(a)
What is the wavelength of a 30 Hz ELF wave in air?
d
(b)
20.
A navy ship sends a radio message of frequency 3 kHz to a
submarine directly below it .The signal travels at 2 x 108 m/s
in water. If the signal takes 3·4 x 10-7 seconds to reach the
submarine calculate the depth, d, at which the submarine is
cruising.
Frequencies of 3 - 30 kHz are called very low frequency (VLF) and
are used by the army for telecommunications.
(a)
A 16 kHz signal is used by the radio operator at Field
Headquarters to send a message to an army patrol during a
field exercise. Calculate the wavelength of
this signal.
(b)
How long will it take this message to reach the patrol which
is 9 km away from Field Headquarters?
(c)
An hour later the patrol sends a radio message to Field
Headquarters giving their new position. The message takes
1·3 x 10-5 seconds to reach HQ. How far is the patrol from
headquarters now?
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Electromagnetic Spectrum 1
In this section the two equations which you will find most useful are
v = fλ
λ
Where
v=d
t
v = average speed in metres per second (m/s)
f = frequency in hertz (Hz)
λ = wavelength in metres (m)
d = distance in metres (m)
t = time in seconds (s).
Helpful Hint
All Electromagnetic waves travel at a speed of 3 x108 m/s
( 300 000 000 m/s ) through space.
A useful unit of distance is the nanometre
1 nm = 0·000 000 001 m = 1 x 10-9 m
1.
Electromagnetic waves with frequencies close to the frequency of
visible light have very short wavelengths often measured in
nanometres (nm).
Convert the following wavelengths into metres:
(a)
(b)
(c)
(d)
5 nm
400 nm
700 nm
1 500 nm.
2. Our eyes can detect visible light with wavelengths ranging from 400
nm to 700 nm. Light with a wavelength of around 400 nm is violet in
colour. Red light has a wavelength of around 700 nm.
Calculate the frequencies of violet light and red light.
3. A doctor examines a patients stomach using a fibrescope. White light
is shone down a bundle of optical fibres called the light guide and
reaches the end of the fibrescope in 1·75 x10-9 seconds. If the light
guide is 35 cm long calculate the speed of the light as it travels down
the fibres.
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Electromagnetic Spectrum 1
4.
f
fra
Peter sprained his ankle playing
football. The physiotherapist uses in
infra-red radiation of wavelength
1·2 x 10 -4 metres to heat the tissue
in his ankle and help it heal. Calculate
the frequency of this radiation.
5.
An elderly patient is suffering from pains in his knees. The doctor
in the hospital takes a ‘heat picture’ called a thermogram of
the knees and detects an inflammation of the joints caused by
arthritis. The infra red radiation being given out by the knees is of
frequency 5 x 1012 Hz. Calculate the wavelength of this radiation.
6.
The ancient Egyptians used ultraviolet radiation from the sun’s rays
to treat the skin complaint acne. Ultraviolet light is still used today
in hospital to treat acne. Calculate the wavelength of UV light of
frequency 8·8 x1016 Hz
7.
Microwaves are part of the electromagnetic spectrum and have
many uses from telecommunications to cooking. Microwaves of
wavelength 12 cm are used in ovens to cook food. The human body
gives out microwaves of wavelength 9 cm which can be detected by
a small aerial placed in contact with the skin. These microwaves
allow doctors to measure the temperature of organs inside the
body.
Calculate the frequency of microwaves emitted from the body.
8.
An argon laser which produces blue/green light of wavelength 500
nm is being used to treat Mrs Doig who suffers from diabetes. The
laser is used to seal blood vessels which have been bleeding into
the eye and damaging her sight. Calculate the frequency of the
light produced by the laser.
9. A low power red argon laser (700 nm) is directed through an optical
fibre to a cancerous tumour in a patients throat. The laser light
activates a drug injected into the patient which will kill the cancerous
cells.
(a)
(b)
What is the frequency of the red light produced by the laser?
Calculate how long it will take for the light to travel 95 cm down
the optical fibre if it travels at a speed of 2·2 x 108 m/s.
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Electromagnetic Spectrum 1
10.
X - rays were discovered in 1895 by Wilhelm Rontgen. X - rays are
now widely used in medicine and dentistry.
John is having an X-ray taken of one of his molars which is giving
him pain. The dentist sets up the X-ray apparatus and goes to
stand behind a lead screen. The X - rays used have a frequency of
2 x1017 Hz.
(a)
Calculate the wavelength of these X-rays.
(b)
How long will it take for these X -rays to travel 10 cm from
the X- ray machine to John’s tooth?
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Electromagnetic Spectrum 2
1.
2.
Describe a use in medicine for each of the following:
(a)
the laser
(b)
X-rays
(c)
ultraviolet radiation.
\
Read the passage below and use it to answer the questions that
follow.
The sun is a star 150 x106 km from Earth which produces enormous
amounts of energy in the form of electromagnetic waves. We can
detect the visible light from the sun with our eyes but we cannot
detect the invisible ultraviolet light which also reaches Earth.
Exposure to the ultraviolet light from the sun can produce a change
in the colouring of the skin which we call a sun tan.
There are three types of ultraviolet radiation. We are constantly
exposed to UVA and we need this for healthy growth and to make
vitamin D in our bodies. UVA light has wavelengths in the range 315
to 400 nm. UVB light has wavelengths in the range
280 to 315 nm. Most of the UVB light from the sun is removed by
the layer of ozone in the atmosphere around the Earth. Scientists
have found that there is a hole in the ozone layer which is allowing
more UVB to reach us on the surface of the earth. UVB can cause a
skin cancer called melanoma. The third type of UV light, with
wavelengths in the range 200 to 280 nm, is called UVC .
People who are going to be exposed to the sun for any length of
time should protect their skin with sun tan cream. An extract from
the back of a bottle of sun tan cream is given on the next page..
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Electromagnetic Spectrum 2
Bronzage cream protects the skin from sun burn,
premature skin ageing and long term damage to the
internal structure of the skin by filtering out the
harmful UVA/UVB rays from sunlight.
Bronzage is water resistant even after a swim of
30 minutes.
(a)
Calculate how long it takes for ultraviolet light to travel
from the sun to Earth.
(b)
Construct a table giving the wavelengths of UVA, UVB and
UVC light.
(c)
Calculate the frequency of the shortest wavelength UVC
light.
(d)
What type of UV light has a frequency of 7·5 x 1014 Hz?
( e)
What range of wavelengths does Bronzage sun tan cream
block?
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Electromagnetic Spectrum 3
1
a) List the members of the electromagnetic spectrum in order
with the largest wavelength first.
b) What do all the members have in common?
2.
How far will radio waves travel in
a) 2 m s
b) 0.25 m s
c) 1 m s.
3..
Calculate the wavelength of waves of frequency
a) 5 GHz
b) 4 MHz
c) 200 GHz.
4.
Calculate the transmission frequency of Radio Scotland
broadcasting on 370 m on the Medium waveband.
Give your answer in MHz.
Waves and Optics (Int 2) – Student Material
12
Electromagnetic Spectrum 4
1.
Describe one use for optic fibres in medicine and explain why using
optic fibres in medicine are an advantage when compared with other
forms of internal examination.
2. The Electromagnetic spectrum is made up of a variety of parts
a. Copy and complete the EM spectrum
b. Identify a suitable detector for each type of radiation and fill in
the lower row of the table
_______ Wavelength
TV &
Radio
waves
Infrared
rays
Low _______
Short ____________
UV
Gamma
rays
______ Frequency
3. Visible light is the part of the EM spectrum that we can see. This
light is seen as white light but it is made up of 7 different colours.
Name the seven colours which make up white light.
4. In industry there are various uses for parts of the EM spectrum. One
such use is to use a type of radiation to detect cracks in metal pipes
which cannot be seen with the human eye.
a. Name the type of radiation that could be used to detect the
cracks.
b. What safety precautions would you need to take when using this
radiation?
c. Give another use for this type of radiation.
5. Using the following frequencies and wavelengths for parts of the EM
spectrum calculate the speed of the waves using the formula v=fxλ
Name
Wavelength
Frequency
Radio wave
3.12m
96.2x106Hz
Visible Red light
750nm(750x10-9m)
4x1014Hz
X Ray
1nm (1x10-9m)
3x1017HZ
What can you say about the speed of the all waves in the EM
spectrum?
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13
Electromagnetic Spectrum 5
1.
Thermal imaging cameras detect infrared radiation.
Give 2 examples of how they or infrared radiation are used:a. by the emergency services.
b. by doctors and physiotherapists.
c. in industry and leisure.
2. Ultraviolet light is sometimes referred to as ‘black light’ and is
both essential for the human body and potentially harmful and it
can kill bacteria.
a. What are the dangers of ultraviolet light and why does our
body need it?
b. Give 2 examples of how it is used either
(i)
by medical practitioners. OR
(ii)
in recreation industry – including sports centres and
night clubs. OR
(iii) in forensics.
3.
Make a list the radiations of the electromagnetic spectrum in
order of increasing wavelength.
a. Add an arrow to your list showing the direction of
increasing frequency.
b. Name a detector for each type of radiation.
4.
What do all the radiations of the electromagnetic spectrum have
in common?
5.
In Summer 2012 the Olympic and Paralympic games were held in
London. TV pictures of the events were transmitted to the USA.
Microwaves carried these signals to a geostationary satellite
36000km above the Earth’s surface.
a. Given that the microwaves had a frequency of 12 GHz
calculate their wavelength.
b. How long did it take the microwaves to reach the satellite?
6.
An infrared wave is used to detect people buried after an
earthquake. It has a wavelength of 2.4 x 10-5m.
a. Calculate the frequency of the wave.
b. The waves are reflected back by a buried casualty.
How far below the rubble is the casualty?
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Electromagnetic Spectrum 5
7.
X-rays have been used for many years by dentists, doctors and
radiographers. More recently their usage has expanded and the
are now used in industry and museums.
a. Explain how an X-ray photograph is taken and explain why
exposure to X-rays should be minimised and what safety
precautions should be taken.
b. State how they effect photograph film and how this can be
used in:
(i)
Medical diagnosis by dentists or doctors.
(ii)
Industry to check welds and aircraft superstructure.
8.
X-ray technology has advanced greatly since Roentgen took the
first X-ray in 1895. CT or CAT scanners are now routinely used in
hospitals, X-ray scanners are used in airports and in radiotherapy.
a. What do CT scanners do and what advantages does this have
over a traditional X-ray photograph?
b. What are they used for in museums and airports and why is
this useful?
c. What is X-ray therapy and what safety precautions must be
taken?
9.
Gamma rays are the most energetic of the electromagnetic
spectrum and can pass straight through the body. They kill
bacteria and damage healthy tissue.
a. How are they used in the medical industry for:
i. In diagnosis? e.g. radioactive tracers, PET scans.
ii. In treatment? e.g. radiotherapy.
b. How are they used in the food industry and what other
industrial uses are there?
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15
Answers
Radio & Television P 2 - 6
1. 31 447 Hz
7.Radio 1-3.07 m
2. 678 733 Hz
Radio 2-3.41m
3. 46 154 m
Radio 3-3.25 m
4. 34 884 Hz
Radio 4-3.12 m
6
5.(a) 1.215 x10 Hz
8. 6.93 x 105 Hz
(b) 8.10 x 105 Hz
9.(a) 9.38 x 107 Hz
(c) 5.48 x 105 Hz
(b) 8.1 x 105 Hz
(d) 8.8 x 107 Hz
10.picture wave0.4m
7
(e) 9.76 x 10 Hz
sound wave0.48m
8
(f) 8.50 x 10 Hz
11. 3 x 109 m
6.(a) 246.91 m
12. 1.33 x 10-4 s
13. 5.4 x 1010 m
(b) 370.37 m
(c) 193.80 m
14. 1.6 x 10-4 s
Electromagnetic Spectrum 1 P 7 - 9
1. (a) 5 x 10-9 m
(b) 4 x 10-7 m
(c) 7 x 10-7 m
(d) 1.5 x 10-6 m
2.violet-7.5 x1014 Hz
red -4.3 x1014 Hz
3. 2 x 108 m/s
4. 2.5 x 1012 Hz
15. 0.01 s
16. 2.67 x 10-5 s
17. 19 500 m
18.(a) 0.47 m
(b) 5.1 x 10-4 s
(c) 255 000 m
19.(a) 1 x 107 m
(b) 68 m
20.(a) 18750 m
(b) 3 x 10-5 s
(c) 3 900 m
6 x 10-5 m
3.41 x 10-9 m
3.33 x 109 Hz
6 x 1014 Hz
(a) 4.27 x 1014 Hz
(b) 4.32 x 10-9 s
10. (a) 1.5 x 10-9 m
(b) 3.33 x 10-10 s
5.
6.
7.
8.
9.
Electromagnetic Spectrum 2 P 10 - 11
1. (a) Laser – bloodless scalpel, removing birthmarks and tattoos,
treating cancer, early diagnosis of illness (experimental)
(b) X-rays – used to detect broken bones, used to create 3-D images
in CAT scans, used to kill cancerous cells in radiotherapy
(c) Ultraviolet radiation – used to sterilize equipment, kill bacteria and
viruses in the air and water used in operating rooms, treat skin
conditions such as psoriasis and vitiligo.
2.
(a) 500 s
(c) 15 x 1015 Hz
(b)
(d) UVA
(e) 280 nm - 400 nm
Radiation
Wavelength (nm)
UVA
UVB
UVC
315 – 400
280 – 315
200 - 280
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Answers
Electromagnetic Spectrum 3 P 12
1.
a)
Radio and TV, Microwaves, Infra red, Visible light,
Ultraviolet, X-rays, Gamma rays
b)
All travel at the speed of light (3 x 108m/s)
2.
a)
600,000m
b)
75,000m
c)
300,000m
3.
a)
0.06m
b)
75 m
c)
0.0015m
4. 0.81MHz
Electromagnetic Spectrum 4 P 13
1 Optical fibres can be used in an endoscope. This is used to see inside a patient.
Lungs, stomach and the intestines can be investigated without surgery. If it is
used to inspect other internal organs the incision used to allow the endoscope
access is much smaller meaning the patient has a shorter stay in hospital and
less to recover from.
2
Radio and TV, Microwaves, Infra red, Visible light, Ultraviolet, X-rays,
Gamma rays
Radio and tv/microwave – tuned circuit and aerial, Infrared – photodiode, visible
light – eye, ultraviolet – fluorescent materials, x rays and gamma rays –
photographic film.
3
Red, Orange, yellow, green, blue, indigo, violet. (ROY-G-BIV)
4.
a) x-rays can be used to detect cracks in welds and pipes.
b) Avoid exposure to x-rays by screening and limiting the time working
with them.
c) Screening luggage at airports for security
5.
Radio wave – 300144000m/s
visible red light – 300000000 m/s
x-ray – 300000000 m/s
Everything in the electromagnetic spectrum travels at the speed of light
(3 x 108m/s)
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Answers
Electromagnetic Spectrum 5 P 14 -15
1(a) Firefighters use thermal imaging cameras to find casualties in
(b)
(c)
2(a)
b(i)
smoke filled rooms and to identify hotspots or the seat of a fire.
They can also be used to find casualties trapped under collapsed
buildings.
Thermograms are used by doctors to diagnose illness – different body
temperatures appear as different colours. If you are unwell the body
would not be at the expected temperature.
Physiotherapists use infrared lamps to heal damaged muscle tissue – this
speeds up the process.
Thermal imaging cameras are used to check buildings for heat loss and
identify where additional insulation is required. They can also be used to
check for overheating in electrical circuitry and equipment. They are
used in the remote controls of TVs and other electronic equipment.
The body needs ultraviolet radiation to manufacture vitamin D.
Excessive exposure can case sunburn and skin cancer.
It can be used to help treat skin conditions such as eczema, psoriasis and
acne. Dentists use it to seal teeth and set fillings. They are also used
to sterilise equipment
b(ii) The are used in tanning studios, to sterilise the air in air
conditioning systems and to kill the bacteria in swimming pool water.
They are used in night clubs and discos to make cloths ‘glow’ – UV causes
some of the chemicals in the clothing materials or the ‘post wash’
residues to fluoresce.
b(iii) No hiding from UV blacklight which plays a vital role from
scene of crime to post mortem.
Ultraviolet lights (blacklights) are extensively used for screening
techniques during forensic investigations at crime scenes and in the
laboratory. It is the first choice when examining biologically
contaminated evidence because UV analysis is non-destructive. It permits
precise images and preliminary identification of evidence prior to other
analytical techniques, i.e. luminol.
Applications range from searching for blood traces, other bodily fluids,
finger prints and foot prints to the revelation of subcutaneous bruising
on the body, including post mortem which may not be visible under other
lighting conditions.
Bodily fluids such as saliva, semen, vaginal fluids, urine and perspiration
will fluoresce under UV blacklight. This makes UV fluorescent inspection
the ideal solution for detecting this type of trace evidence at crime
scenes or on evidence collected as a scene, e.g. clothing, bed linen, towels
and other objects.
UV blacklight inspection will also detect some drugs, for example LSD.
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Answers
3(a)
TV& Radio, Microwaves, Infrared, Visible light, Ultraviolet, X-rays,
Gamma rays.
(b)
Gamma rays, X-rays, Ultraviolet, Visible light, Infrared, Microwaves,
TV&radio.
4.
They all travel at 300 000 000m/s the speed of light.
5
(a) 0.025m
(b)
0.12s
6
(a)
1.25 x 1013Hz
(b) 1.8m
7.
Gamma Rays – Geiger Muller tube, photographic film, gamma
camera, scintillation counter.
X-rays – Photographic film.
Ultraviolet light – Fluorescent paint, photodiodes.
Visible light - Photographic film.
Infrared – Blackened thermometer.
Microwaves – Diode probe.
TV & Radio – Aerial.
8(a) Photographic film is placed underneath the patient, the X-ray machine is
placed above the patient and X-rays are fired at them. X-rays will pass
through the body and be detected by the
photographic film. X-rays are
absorbed by bone and tissue, the blacker the film the greater the number of
X-rays reaching it. So
a healthy bone will appear white and a broken bone
will have a
dark line where there is break.
X-rays will damage healthy tissue so exposure to X-rays must be
minimised. Sometimes lead blankets are placed over the parts of
the
body not being examined to prevent unnecessary exposure.
Radiographers
and dentists will leave the room while an X-ray is
being taken and may
observe through leaded glass windows.
b(i)
Dentists can check for tooth decay – this appears as a dark shadow in
apparently healthy teeth, for undescended teeth and fillings. Doctors
can check for broken bones, scarring on the lungs – common when
patients have or have had tuberculosis and for certain cancers – the
denser cancerous growths absorb more X-rays than healthy tissue or
foreign bodies inside the body.
b(ii) Metals will absorb X-rays so cracks in welds or superstructure will appear
in the same way as broken bones do
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Answers
9(a)
CT scanners cut the body up into thousands of X-ray slices. The
information is passed to a computer which can put the slices together to
produce a 3-D picture. Unnecessary information can be removed and
exact pictures of tumours and broken bones can be produced. This allows
exact doses of X-rays and other treatments to be calculated, surgical
routes and the restructuring of bones to be planned.
(b)
They can show what is inside mummies, to check foe crack and damage in
artefacts etc without having to take them apart and causing further
damage.
They can show what is inside luggage, what undergarments a person is
wearing, what is in their pockets... This means that any suspect items can
be removed and investigated in more detail.
(c)
This is quite simply using high energy X-rays to kill tumours. The X-rays
are fired from a rotating ‘gun’ and are focussed on the tumour. As the
machine rotates around the body the exposure to healthy tissue is
minimised.
10a(i) Radioactive chemicals are dissolved or placed in a liquid that is tied to
particular hormones. These are either injected into the body or
swallowed and a gamma camera will detect the gamma rays as they pass
through the body and their route can be plotted. The chemicals will
concentrate in a particular organ and this can give information regarding
blood flow, blockages and the presence of particular tumours.
a(ii) This is quite simply using gamma rays to kill tumours. The gamma rays
are fired from a rotating ‘gun’ and are focussed on the tumour. As the
machine rotates around the body the exposure to healthy tissue is
minimised.
(b)
They are used to kill the bacteria that causes foods to rot – this extends
shelf life and to delay or prevent the germination of some grains.
They are used to sterilise surgical instruments and other equipment, to
check the thickness of paper and other materials and to examine shipping
crates both before leaving and after arrival at ports.
GMV Science. Photocopiable only by the purchasing institution.
Waves and Optics (Int 2) – Student Material
SIC Development group PB
20