radiations unit - lessons

8/3/2019 Radiations Unit - Lessons

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Unit 4: Radiations Let there be light! Lesson 1

Light for sightWithout light, we cant see. Pretty obvious, really. But whats actually going on

when we see something?

A couple of basic points.

Light travels as rays Light rays travel in straight lines.Draw a light ray on this diagram to show how the girl sees the light bulb. Use a

ruler!

But what about objects that dont give off light? How do we see those?

Draw two light rays on this diagram to show how the girl sees the frying pan.Think carefully.

Use your diagrams to complete these sentences.

All visible objects either g____ o___ light (like a light bulb) orr______ light (like a book).

This light then t______ to the e___.Knox Academy Physics Department 1


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Unit 4: Radiations Let there be light! Lesson 1

Shiny stuffWhy do some objects like aluminium foil look shiny whilst others look dull?

Objects dont always reflect all of the light that falls on them. They can absorbsome of it.

Complete the table and the bar chart to show the reflectivity of different

surfaces.

surface % of light reflected % of light absorbed

mirror 95 5

brown carpet 25

sheet of glass 17

tarmac 70

wooden table top 46

white gloss paint 68

Title: ____________________________

Knox Academy Physics Department 2

0

10

20

30

40

50

60

70

80

90

100

%o

flightreflected


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Unit 4: Radiations What is light? Lesson 1: extra

Looking into lightYoull need a ray box with a single slit, a power supply, a triangular prism and a

screen made of white card.

Set up your equipment like this.

Point the light ray near the top corner of the prism. Now turn the prism slowly,

keeping an eye on the screen.

1. Describe what you see.

2. Where have you seen this sort of pattern before?

3. List the different colours you can see.

MnemonicsA mnemonic is a way of remembering a list. It works like this:

My Very Excellent Mulberry Jam Should Use No Preservatives.

(Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto.)

Make up your own mnemonic for the colours of the rainbow:

Red, Orange, Yellow, Green, Blue, Indigo, Violet

Knox Academy Physics Department

power

supply

(12 V)ray box

prism

light ray

screen

3


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Unit 4: Radiations What is light? Lesson 1: extra

Now you see itLight is a wave. Its a bit like waves in water, but there are some big differences.

In water, the distance between the top of one wave and the top of the next the

wavelength might be a few metres. For light, the wavelength is about0.0000005 metres you can fit two million wavelengths into a single metre.

Light also travels amazingly fast in fact, its the fastest thing there is. The

speed of light is 300,000,000 metres per second a beam of light could go

round the Earth seven times in a single second at this speed. Because light

travels so fast, we never notice any sort of delay when we switch on a light.

Light from the Sun is white in colour. But when the sunlight is split up say by

raindrops in a rainbow we see that light is actually made up of different

colours mixed together. The different colours have different wavelengths. Blue

light has the shortest wavelength 0.0000004 metres. The wavelength of red

light is almost twice as long at 0.0000007 metres.

Questions

1. What is light?

2. On this picture of a wave, draw an arrow to show the wavelength.

3.

Use the information in the second paragraph to work out the

circumference of the Earth.

4. Green light has a wavelength between red and blue. Write down a

possible value for the wavelength of green light.

5. The Moon is about 400,000,000 metres away. How long would it take a

ray of light to travel to the Moon? (time = distance speed.)



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Unit 4: Radiations Reflection Lesson 2

Mirror, mirrorYou learnt in the last lesson that we see most objects because light reflects off

them. This is because:

Light can be reflectedLight doesnt just reflect off mirrors, but because mirrors are flat, it makes it

easier to study what goes on.

The law of reflectionIn this experiment, youll find out exactly what happens when a light ray hits a

mirror.

1. Collect a ray box, a power supply, a single slit and a small mirror.

2. Place the mirror on this page where shown.

3. Shine rays of light along the different lines. Use a sharp pencil and a ruler

to draw in the reflected rays. Label them A1, B1 and C1.


this line is called the normal

A

B

C

mirror

5


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Unit 4: Radiations The Hall of Mirrors Lesson 2: extra

Funny faceThe Law of Reflection only works when a mirror is flat. If a mirror is curved,

you get all sorts of strange effects.

Collect a flexible mirror.

1. Bend the mirror towards you, like this.

Look in the mirror. Make a sketch of what you see.

2. Bend the mirror away from you, like this.

Look in the mirror. Make a sketch of what you see.

3. Find out how to give yourself a thin face.

Make a sketch of your face, and show

how you bent the mirror.



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Unit 4: Radiations The Hall of Mirrors Lesson 2: extra

ReflecTionMirrors can be used to investigate symmetry. (Symmetry means the same.)

Put the edge of your plastic mirror against the dotted line in this letter T.

TIf you look in the mirror, you should still see a T. The dotted line is a line of

symmetry.

Now try this T puzzle. A mirror might help or maybe not.

Collect a copy of the shapes above.

Cut them out carefully, then arrange them to make a letterT. You cant fold oroverlap the shapes.



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Unit 4: Radiations Total Internal Reflection Lesson 3

A see-through mirror?You might think that the whole point about glass is that light travels straight

through it. But if you arrange things properly, a piece of glass can act like a

mirror.

Experiment 1

Collect a block of glass.

Hold the glass horizontally in front of your eyes, and look down through the

glass onto the bottom surface.

You should see a reflection of whatever is on the other side of the glass.

This is called total internal reflection, and it happens whenever light strikes

glass at a big enough angle.

Experiment 2Your teacher will show you how light can travel through a long piece of clear

plastic. This is called an optical fibre.

On this diagram, draw the path of the ray of light in the optical fibre.

Mark with an X the points where the light is totally internally reflected.

Light can travel down an optical fibre.Knox Academy Physics Department

look this way see a reflection of

whatevers here

9


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Optical fibres in medicineDoctors dont want to cut people open if they can avoid it but how else can

you see if something is wrong? You can use a fibrescope.

A fibrescope has two bundles of optical fibres.

The first bundle is used to pass light down

into a patients body perhaps into the lungs.

The light reflects off the lungs and travels

back up the other bundle of optical fibres to

the doctors eye. This means the doctor can

see inside the patient.

When a fibrescope is used to examine the lungs, it is called an endoscope.

When it is used to examine the digestive system, it is called a gastroscope.

Optical fibres can also be used to help treat certain types of cancer. Lasers can

be used to burn away cancerous growths. But if the growth is in the stomach, a

doctor would need to cut open the stomach to get to the growth.

Because lasers are a form of light, they can be passed down optical fibres by

total internal reflection. A fibre can be passed down the throat and into the

stomach. When it is in the right place, the laser is fired to burn away the growth.

1. What is the job of each bundle of optical fibres in a fibrescope?

2. What is the difference between a gastroscope and an endoscope?

3. How does the laser light travel down an optical fibre?

4. Why do doctors prefer to use optical fibres for laser treatment?



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Unit 4: Radiations Christian Huygens Lesson 3: extra

Working out lightIn the 17th century, there were many arguments about what light was and how it

worked. Sir Isaac Newton thought he knew, but for once, the great scientist had

got it wrong. A Dutch scientist called Christian Huygens was the first person toexplain how light travelled as waves.

Collect Info Card 4.3 on Christian Huygens. Use it to complete the Huygens

Fact File and answer the questions.

Questions

1. Who helped Huygens become interested in science?

2. Why did Huygens write so many letters to other scientists?

3. What was the title of Huygens first book?


Date of birth: ________________

Date of death: _______________

Place of birth: _______________

University: __________________

Famous discovery 1

____________________

____________________

____________________

____________________

Famous discovery 2

____________________

____________________

____________________

____________________

12


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Unit 4: Radiations Christian Huygens Lesson 3: extra

4. What amazing astronomical discovery did Huygens make?

5. What topic did Huygens work on in the 1650s and who else was

working on it?

6. What was Newtons explanation for light?

7. What was Huygens explanation for light?

8. Huygens ideas were correct, but were ignored for some years. Can you

explain why?

9. What book did Huygens publish in 1673?

10. Why was this book so important to other scientists?

Can you solve Huygens anagram?

RUST GRAINS NASH



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Unit 4: Radiations Lenses Lesson 4

Lenses for seeingAs you get older, your sight usually gets worse. Theres not much you can do to

stop this happening its a condition called middle-aged presbyopia.

So if you dont wear glasses already, you probably will when youre older. So

how do glasses work to correct our sight?

The two pieces of glass or plastic in front of your eyes are called lenses. Lenses

turn up all over the place in telescopes, for example.

Lenses come in two main types.

Converging lenses look like this. (Theyre also called convex.)

Diverging lenses look like this. (Theyre also called concave.)

Questions1. What is the name of the condition that causes sight problems, as you get

older?

2. List three things, not mentioned above, that use lenses.

3. Name the two main types of lens.

4. What are the other names for the lenses?



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Unit 4: Radiations Lenses Lesson 4

Lenses and lightIn this experiment, youll find out how the different types of lenses affect light.

Collect a power supply, ray-box, triple slit, converging lens and a diverging lens.Set it up like this:

Put the converging lens in front of the ray box. In the box below, draw the lens

and show what it does to the light rays. (Use a ruler for the light rays!)

A converging lens b_______ the light rays t__________.Now remove the converging lens and put the diverging lens in front of the ray

box. In the box below, draw the lens and show what it does to the light rays.

A diverging lens s________ the light rays a_______.Knox Academy Physics Department

power

supply

(12 V)ray box

three light rays

lens

15


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Unit 4: Radiations More on lenses Lesson 4: extra

In Lesson 4, you learnt about the effect that converging and diverging lenses

have on rays of light.

But not all converging or diverging lenses are exactly the same shape. Some are

more curved than others. Does this have an effect?

What to do

1. Collect a power supply, ray-box, triple slit, and different converging and

diverging lenses.

2. Choose a lens, place it on this lesson sheet, and draw around it.

3. Shine three rays of light through the lens.

4. Draw the rays of light that go into the lens and come out of the lens.

5. Repeat this with as many lenses as you have time for.



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Unit 4: Radiations More on lenses Lesson 4: extra

Have you found any sort of pattern? How does the amount of curve in the lens

affect the rays of light? Explain what you have found out.



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Unit 4: Radiations How do you see? Lesson 5

Sight problemsThe two most common eye problems are called short

sight and long sight.

Short sight is when you cant see far away things

clearly.

Long sight is when you cant see nearby things clearly.

The cause of these problems is usually that the eyeball hasnt grown properly. In

short-sighted people, the eyeball is too long. In long-sighted people, the eyeball

is too short. This means that the lens in the eye cant focus light on the retina

the screen at the back of the eye.

Lets have a more detailed look.

Good sight

The lens in the eye focuses

light right on the retina. You

see everything clearly.

Short sight

The eyeball is too long. The light

comes to a focus in front of the retina.

Anything in the distance looks fuzzy.

Long sight

The eyeball is too short. The light comes

to a focus behind the retina. Anything

nearby looks fuzzy.


lens of eye retina

light focused

on retina

eyeball

light focused

behind retina

light focused infront of retina

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Unit 4: Radiations How do you see? Lesson 5

Use the information on the other side of this sheet to answer these questions.

1. What are the names of the two main sight problems?

2. What is the usual cause of short sight?

3. What is the usual cause of long sight?

4. A man needs glasses to read the newspaper. Is he short-sighted or long-

sighted? How do you know?

5. A woman needs glasses to read road signs when she is driving. Is she

short-sighted or long-sighted? How do you know?

6. What is the screen at the back of the eye called?

7. If a person has good sight, where does the light focus in their eye?

8. In Johns eyes, the light focuses before it gets to the retina. Is he long-

sighted or short-sighted?

9. Can you name any other sight problems?



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Unit 4: Radiations Quiz time Lesson 5: extra

AnagramsSolve the anagrams all the answers are words connected with light and lenses.

FLECTER_________________ GIVEGRIND__________________

VEAW _________________ RORRIM __________________

CLAPOIT _________________ GHOSTTRISH _________________

SNEGYUH _________________ TRAINE __________________

A to Z (well, some of them)

A: what a black piece of paper does to light __________________

C: a lens that brings light rays together __________________

D: a lens that spreads light rays apart __________________

E: used to look at the lungs __________________

F: we see clearly if light rays are in __________________

G: used to look at the digestive system __________________

H: famous scientist from The Netherlands __________________

L: when nearby things are blurred __________________

M: when people get presbyopia __________________

N: a dotted line drawn at right angles to a mirror __________________

O: a type of fibre __________________

R: the title of this topic __________________

S: when far away things are blurred __________________

T: how light can bounce down glass __________________

W: light travels as a __________________



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Unit 4: Radiations Curing sight problems Lesson 6

Lenses for lifeGlasses or contact lenses can be used to fix sight problems. But

how are different lenses used to fix different problems?

Your teacher will show you a demonstration with a model eye.

We can make the model short-sighted or long-sighted, and see

which lenses are needed to fix the problems.

Watch the demonstrations, then answer the questions.

1. Where on the model do you see the image?

2. How can you tell that the model eye is seeing a clear image?

3. How do we make the eye short-sighted?

4. What happens to the image when we make the eye short-sighted?

5. What type of lens is used to correct the short sight?

6. How do we make the eye long-sighted?

7. What happens to the image when we make the eye long-sighted?

8. What type of lens is used to correct the long sight?



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Unit 4: Radiations Curing sight problems Lesson 6

This diagram shows how a short-sighted eye cant focus on things far away.

Now weve added a diverging lens. Draw light rays on the diagram to show how

the eye can now focus. Use a ruler!

This diagram shows how a long-sighted eye cant focus on nearby things.

Now weve added a converging lens. Draw light rays on the diagram to show

how the eye can now focus. Use a ruler!

A converging lens can be used to correct long sight.

A diverging lens can be used to correct short sight.



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Unit 4: Radiations Other uses for lenses Lesson 6: extra

Different viewsAlthough one of the most important uses of lenses is in glasses, there are lots of

other ways we can make use of them. Here are a few for you to try.

Experiment 1: the telescope

Basic telescopes use two lenses. The one you point at whatever

youre looking at is called the objective lens. The one next to

your eye is the eyepiece lens.

Heres how to make a very simple telescope.

Collect a small fat lens for the eyepiece, a larger thinner lens for the eyepiece

and two lens stands.

1. Set them up like this.

2. Look through the eyepiece lens towards the objective lens.

3. Adjust the distance between the two lenses until you get a sharp clear

image.

Questions

1. What do you notice about the image you see?

2. Try looking through the telescope the wrong way. What do you see

now?

3. Maps of the Moon are published upside-down. Why do you think this is?


eyepiece lens objective lenslook this way

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Unit 4: Radiations Other uses for lenses Lesson 6: extra

Experiment 2: the magnifying glass

Scientists have always needed ways to make small things look

bigger. Many years ago, they used drops of water as magnifying

glasses. This experiment is a bit easier.

You need the two lenses from the last experiment.

1. Use the lenses in turn to examine the print on this page. Can you read this?

2. Try changing the distance between the lens and the paper.

3. Try changing the distance between the lens and your eye.

Questions1. Which lens magnified most the thin lens or the fat lens?

2. Which lens did you have to hold nearest the page to see clearly?

Experiment 3: the camera lens

The lens in a camera works in a similar way to the lens in the eye. It has

to focus an image onto the photographic film at the back of the camera.

1. Pin a piece of plain paper to the wall opposite the window. (The

paper is like the photographic film.)

2. Hold one of the lenses near the paper. Make sure your hand or body

doesnt block the light from the window.

3. Move the lens in or out until you see sharp image of the window on the

piece of paper. Try both lenses.

Questions

1. Which lens gave the smallest image on the paper?



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Unit 4: Radiations Lasers Lesson 7

I expect you to die, Mr BondYouve probably seen the film. James Bond strapped to a table. A

red laser beam is gradually moving up the table, cutting it in half.

In just a few seconds, its going to cut James Bond in half

We see images of lasers all the time on films. Star Wars battle cruisers fire green

bolts of laser light at each other. Whole planets are destroyed by powerful laser

beams. But what are lasers?

Laser stands for:

Light

Amplification

by the Stimulated

Emission

of Radiation.

That sounds rather complicated what does it really mean?

A laser is a concentrated beam of light of just one colour.Laser light doesnt spread out, like light from a torch does. Because all the light

energy is concentrated in one place, powerful lasers can burn through sheets of

steel or shoot aeroplanes out of the sky. But most lasers are much less powerful,

though they are just as useful. People who have a disease called diabetes may

suffer from leaking blood vessels in the eye. This can cause blindness. A laser

can be used to heat up and seal the blood vessels, saving the persons sight.

Lasers can be very dangerous. The problem with many laser pens is that they are

too powerful. If they are shone in someones eye, the laser light can burn the

retina. Schools must follow special rules when using lasers, to make sure that

nobodys eyes are hurt. The sign at the top of this page shows that a laser is

being used.

Because laser light doesnt spread out and get weaker, it can travel huge

distances. During one of the moon landings in the 1970s, a mirror was fixed to

the Moons surface. Scientists can now fire a laser at the mirror, although its

400,000 kilometres away. The laser light bounces off the mirror and travels back

to Earth. By measuring how long this takes, scientists can work out exactly how

far away the moon is to the nearest centimetre!

Now watch the laser demonstration. Afterwards, answer the questions on theback of this sheet.



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Unit 4: Radiations Review Lesson 7: extra

Check what youve learntThe questions below cover all the things you should have learnt in lessons 1 - 7.

See how many questions you can answer from memory then read over yournotes and correct any answers you got wrong or missed out.

1. Complete this sentence.

All visible objects either g____ o____ light or r_______ light to the e___.

2. How do light rays travel?

3. What can you say about the angle at which light hits a mirror, and the

angle it reflects at?

4. What is the name of the imaginary line we draw at 900 to a mirror?

5. Write down the seven colours of the rainbow, in order.

6. Write down one practical use for optical fibres in medicine.

7. Name the two types of lenses.

8. Jill cant see things clearly that are close to her. Is she short-sighted or

long-sighted?



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9. Light from distant objects entering Jacks eye comes to a focus in front of

the retina. Is he long-sighted or short-sighted?

10. What type of lens is used to correct long-sight?

11. What type of lens is used to correct short-sight?

12. Draw a converging lens and show how it affects parallel light rays

travelling through it.

13. Draw a diverging lens and show how it affects parallel light rays

travelling through it.

14. What does LASER stand for?

15. How many colours of light does a laser produce?

16. Write down one practical use for lasers.

My score out of 16: ____



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Unit 4: Radiations X-rays Lesson 8

The unknown raysIn the 1870s, a German physicist called Wilhelm Roentgen

took the very first X-ray picture of his wifes hand. No-one

really knew what these rays were they were called Xraysbecause the letter x is used in maths for something that is

unknown.

Some companies tried to take advantage. A company in Paris

sold pairs of X-ray glasses for seeing through clothes. Although this was

nonsense, another company started selling X-ray proof underwear for ladies.

It was hard to understand X-rays because:

X-rays are invisible to the naked eyeWe cant see X-rays directly we can only see their effects.

X-rays can be detected with photographic film.X-rays are part of the same family as light, but have a much shorter wavelength.

This means they can pass through things that light cant. X-rays can pass

through soft skin and tissue easily, but they are absorbed by bones.

Questions

1. Look at the X-ray picture above. What is the lump on one of the fingers?

2. Heres how an X-ray is taken. Copy the labels into the right boxes.

Labelsbody part X-ray film X-ray machine X-rays X-rays not absorbed by bones



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Unit 4: Radiations X-rays Lesson 8

Looking at X-raysTake a careful look at each of the X-ray prints in the room. For each one, write

down what part of the body you think it shows. Describe any other interesting

details you see can you find the zip on one of the X-rays?

X-ray

numberwhat does it show?

1

2

3

4

5

6

7

8

9

10

11

12



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Unit 4: Radiations Digital X-rays Lesson 8: extra

The power of computersNowadays, X-rays can be converted into computer images. This has many

advantages, such as being able to get a 3D view. But how can a computer image

be made from a black-and-white X-ray?

A scanner passes over the X-ray, section by section. If it sees a black area

below, it sends a 0 to the computer. If it sees a white area, it sends a 1 to the

computer. The computer uses this information to build up a picture.

What to do

Here is the information from a scanner.

0000010000,0001010100,0101010100,0101010000,0101010100,0101010101,

0111111101,0111111101,0111111111,0111111111,0111111111,0001111100,

0001111100,0001111100,0001111100

Work across, row by row. If the number is 0, shade in the box in the grid. If the

number is 1, leave it blank. The first row has been done for you.

What have you taken an X-ray of? Is there a problem?



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Unit 4: Radiations Digital X-rays Lesson 8: extra

Making the right choiceHere is a table of information about different digital X-ray machines. Study it

carefully, then use it to answer the questions.

Make CostDelivery

time

X-rays per

hournotes

X-cel 450,000 3 months 16 bone X-rays only

Ray-guard 615,000 8 weeks 14 bones + lungs

Supa-view 1,250,000 6 months 30 all types of X-ray

iXs 650,000 2 weeks 21may not be used for

skull x-rays

X-Camera 830,000 1 month 20 all types of X-ray

1. Why is the Supa-view the most expensive machine?

2. How many X-rays can the X-Camera take in 8 hours?

3. Which machine would be unsuitable for a hospital dealing with sportsinjuries? Explain your choice.

4. Why is the X-cel the cheapest machine?

5. The X-ray machine at the Parkfield Chest Hospital needs to be replacedurgently. The hospital deals with many emergency cases. The hospital

manager is worried about the budget.

Which X-ray machine should they choose. Explain your choice.



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Unit 4: Radiations Using X-rays Lesson 9

X-rays in medicineMost of us think of X-rays as pictures of bones. Doctors use X-rays to find out if

a leg is fractured or an ankle is broken. This is a very important use of X-rays,

but there are other ways that they can be used in medicine.

CAT scanners

CAT stands for Computer Aided

Tomography. A CAT scan takes

hundreds of separate X-rays of the

body, slice by slice. This gives doctors

a much better view of things like

tumours growing in the body.

Killing and curing with X-rays

X-rays are dangerous because they can damage living cellsHaving one or two X-rays is not a problem. Only a few of your cells will be

damaged, and your body will soon repair them. However, a very big dose of

X-rays could make you seriously ill or kill you.

The people in hospitals who take X-rays are called radiographers. They have to

be protected from the X-rays they work with. Before the X-ray machine is

switched on, they go behind a lead-lined door leaving you all alone!

X-rays can also be used to kill cancerous tumours. Beams of X-rays are fired at

the tumour from different directions. This kill the unhealthy cells, without

damaging too many healthy cells.

1. Have you ever had an X-ray? Which part of your body?

2. What is the main advantage of a CAT scan compared to a normal X-ray?

3. If you have a tooth X-ray at the dentist, you have to wear a lead-lined

apron. Why?



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Unit 4: Radiations Using X-rays Lesson 9

X-rays in industryAlthough we usually think of X-rays as something to do with medicine, they

have many other uses.

Airport security

If youve ever flown abroad, youll know that your

luggage gets X-rayed. The X-rays will pass through

the sides of your suitcase, but will be absorbed by

any metal objects in your case.

Testing pipes

The UK is held together by pipes. Our

water, gas and sewage pass down

pipes, and its important that they dont

leak. Pipes can be X-rayed to show up

any cracks or splits.

Welded joints

The bodywork of most cars is made from separate

metal sections that have been welded together. Its

vital that the welded joints are strong and have noflaws. X-rays can be used to examine welded joints

to look for any signs of damage.

1. Name the different items you can see in the suitcase.

2. Can you see any damage on the pipe? How do you know?

3. When you travel abroad, its a good idea not to put camera film in your

suitcase. Why not?



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Unit 4: Radiations X-raY-quiZ Lesson 9: extra

X-ray wordsearchAnswer the questions. Then find the answers in the grid.

1. The discoverer of X-rays.2. A type of X-ray scan.

3. X-rays can damage living _____ .

4. The person who gives you an X-ray.

5. They show up white on an X-ray.

6. Compared to light, X-rays have a very short _____________.

7. X-rays can be detected by ______________ ____. (2 words)

8. At the airport, X-rays are used to check __________.

9. The first X-ray ever taken showed a _______.

10. We cant see X-rays because they are _____________ .11. X-rays can be used to kill these.

12. The X in X-ray stands for _____________.

13. X-rays were discovered in the nineteenth _____________.

14. This metal can be used to absorb X-rays.

A Y W P H U U I X C W Q U O M L D P E Z

G F R O E N T G E N S V Y L A Q Z H O IO U L R E H P A R G O I D A R B R O E M

Q W E R T Y U I O P A S D F G H J T B K

C X C B E G H K W I O S E V M X E O E R

I C E N T U R Y R E A L T Y U N N G I K

B E L B R I S A E G H H U L P E C R Z M

T R L N H G H N N V T N M O S E D A A Q

G C S R F T G A U G O L O D E W S P V A

P O I U Y T R E N J N G U D E R S H A Z

U O W C N U D E X D Y U R K E S S I N WL N B R O N L F A A X Z S O L R N C P L

E X K R M E G A G G U L P A B V E I L F

O L R N V D Q Y B K O P E C I D O F S N

F G H A O J H G L O R P O E S S Z I J U

J Y W G X W Q U E T P L I B I S A L D R

L S B Y Q E N B A A T L F T V R V M A D

Z Q W X E C R V T C B Y N U N M I L E P

B V F R T Y H G W S I O P N I A C Q L S

Y H P A R G O M O T B X W P L U T D A M



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Unit 4: Radiations Radioactivity Lesson 10

Danger - radioactivitySome substances, like uranium, are radioactive. This means they break down by

firing out particles and rays. These particles and rays are the things that can

make radioactivity dangerous. There are:

alpha particles ( )

beta particles ( )

gamma rays ( )

(Gamma rays are also called gamma radiation it means the same thing.)

The symbols , and are the first three letters of the Greek alphabet.

These particles and rays are invisible but we can detect them. Like X-rays,

they affect photographic film. But an easier way is with a Geiger-Muller tube.

Youve probably seen these in films they make clicking noises when they pick

up radioactivity.

Radioactivity close up

Your teacher will demonstrate some experiments with radioactive sources.Watch the experiments carefully, and use the information you get to complete

this table.

type of

radioactivity

count rate (slow,

medium, fast)

how far does it

travel in air?

what is it

absorbed by?

alpha

beta

gamma -



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Unit 4: Radiations Radioactivity Lesson 10

Questions1. Which type of radiation was stopped very easily?

2. Would this type of radiation be able to penetrate your skin?

3. Why could the alpha particles not travel very far through the air? What

was stopping them?

4. Which radioactive source was the most penetrating?

5. Can gamma radiation travel through your body?

6. Describe how the radioactive sources are stored.

7. List three safety rules when using radioactive sources.

8. Smoke alarms use a radioactive source. If the radioactive particles are

absorbed by smoke, the alarm goes off. Which type of radioactive source

is used in smoke alarms? Explain your answer.



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Unit 4: Radiations Its all Greek to me Lesson 10: extra

Different alphabetsIf youve ever been to Greece, youll know that they use a

different alphabet. (And did you know that the word

alphabet comes from the first two Greek letters alphabeta.) You might have learnt the Greek letter called pi.Its used in maths for working out things about circles.

Physics uses the Greek alphabet because there arent enough letters in the

normal alphabet to stand for all the things we measure in physics.

Heres the full Greek alphabet and the nearest English letter.

alpha a nu n

beta b xi x gamma c or g omicron o

delta d pi p

epsilon e ro r

zeta z sigma s

eta h tau t

theta th upsilon u

iota i phi f or ph

kappa k chi c

lambda l psi y

mu m omega w or v

Questions

1. Write your full name using the Greek alphabet.

2. Write down the name of your favourite football team in Greek.

3. Can you translate this?

4. And this:



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Unit 4: Radiations Gamma rays close up Lesson 11

Dangerous but usefulGamma rays are similar to X-rays in many ways.

Gamma radiation is invisible to the naked eye.

Gamma radiation can kill or damage living cells.However, gamma rays are even more powerful than X-rays. Think back to

lesson 10 and youll realise:

Gamma radiation can pass through most materials.Absorbing gamma raysIn lesson 10, pieces of lead were needed to absorb the gamma rays. How does

the thickness of lead affect the number of gamma rays?

Watch the experiment, and record the results in this table. Then draw a graph.

thickness of lead (mm)

gamma rays in 1

minute

Title: _______________________


thickness of lead (mm )

gammaraysin1min

ute

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Unit 4: Radiations Gamma rays close up Lesson 11

Questions1. What is the name of the device used to count the gamma rays?

2. Why did your teacher start by using a sheet of aluminium?

3. What happened to the number of gamma rays as the lead got thicker?

4. How much lead was needed to reduce the gamma rays by half?

5. How much lead do you think would be needed to stop the gamma rays

altogether?

6. What are the disadvantages of using lead to absorb gamma rays?

7. What other materials could be used to absorb gamma rays?

8. Why can gamma rays be dangerous?

9. Gamma rays from the rocks and soil are passing through your body all the

time. Why do you think that they dont damage your health?



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Unit 4: Radiations Using gamma rays Lesson 11: extra

Gamma radiation in medicineRead the following passage, then answer the questions.

Gamma rays kill or damage healthy cells. Although this means they can harmhuman health, we can make use of them.

Gamma rays can be directed at cancer tumours. The gamma rays kill the cancer

cells, without doing too much damage to the healthy cells around the tumour.

Gamma rays can also be used to sterilise surgical instruments. The gamma rays

will kill any bacteria that might be living on the instruments. Because gamma

rays pass through most materials, things like scalpels can be sealed in plastic

bags and then exposed to gamma rays. The gamma rays pass through the bag

and kill any bacteria. As the scalpel is in a bag, no new bacteria can get in.

Gamma rays also help us to see what is happening in the human body. A patient

with a heart condition might have a tracer injected into their bloodstream. The

tracer emits gamma rays as the blood travels around the body. These gamma

rays easily pass through the body to the outside. A special type of camera called

a gamma camera can pick up these gamma rays and use them to make a picture

of how the blood is flowing. Doctors can then find problems such as blockages.

The tracers do not keep on emitting gamma radiation for very long. This wouldharm the patient. The strength of all sources of gamma rays decreases over time.

The sources used for tracers decrease very quickly.

1. How can gamma rays be used to treat cancer?

2. How can gamma rays kill bacteria inside plastic bags?

3. Why can alpha and beta not be used to make tracers?

4. Why is it safe to inject someone with a tracer that emits gamma rays?



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Unit 4: Radiations Using gamma rays Lesson 11: extra

Gamma radiation in industryRead the following passage, then answer the questions.

In Russia, there are pipelines thousands of kilometres long

carrying oil. These pipelines often run underground.

Sometimes, the pipeline develops a leak. But how do you find the leak without

digging up the pipes? Engineers can add a chemical to the oil that emits gamma

rays again, this is called a tracer. As the oil travels along the pipe, it will give

off gamma rays. The gamma rays pass through the pipes and the rocks and soil,

and are detected on the surface. By studying what happens to the gamma rays,

engineers can work out where the leak is. Only a small section of the pipe needs

to be dug up.

Because the gamma rays will have to pass through the metal pipes and manymetres of soil, very strong sources of gamma rays have to be used. They must be

used very carefully. The engineers keep as far away from the sources as

possible, and handle them for as short a time as possible. Thick lead shielding is

used to protect the engineers.

1. What is a tracer?

2. Why does such a strong gamma ray source have to be used?

3. List three safety precautions the engineers will follow.

4. Will the strength of gamma source decrease quickly or slowly? Explain

your answer.



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Unit 4: Radiations Gamma rays all around us Lesson 12

You cant see it, but its thereSome people think that gamma rays are man-made that before scientists in

white coats started making bombs, there werent any gamma rays.

Not true.

Gamma rays have been around since the start of the Universe. There were

gamma rays on Earth well before humans showed up. And theyre still here.

There is gamma radiation present in our surroundings.Thats right. The bricks that make your home, the air you breathe, the food you

eat even you yourself give off gamma radiation.

This radiation that surrounds us is called background radiation.

Measuring background radiation

Your teacher will set up an experiment to measure the background radiation

level in the room.

Draw a labelled diagram of the equipment. Write down how many minutes the

experiment ran for, and how many counts were recorded.

Now use the results to calculate the average number of counts per minute.

The background radiation level in the room is ________ counts per minute.


Time experiment was run for = _____ minutes

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Unit 4: Radiations Gamma rays all around us Lesson 12

Sources of background radiationRead the following passage. Use the information in it to complete the table.

The average person in Britain gets a dose of about 2000 units of backgroundradiation every year. Over half of this 1300 units comes from radon and

thoron gas. These gases are given off by rocks and soil. They are very heavy

gases, and collect under the floorboards of houses. People who live in Cornwall

get a bigger dose than other people because the rocks in these areas are more

radioactive. We receive about 300 units of radiation from food and drink. Tea,

coffee and brazil nuts give off more radiation than most other foods.

Some of the dose comes from outer space. Cosmic rays from space are mostly

absorbed by the Earths atmosphere, but enough get through to give us a dose of

about 250 units a year. Airline pilots get a bigger dose because the atmosphere is

thinner at high altitude.

Some sources of background radiation are man-made. The many medical and

industrial uses of radiation average out at 140 units per person per year.

However, this is an average. Someone having treatment for cancer would

receive a far higher dose. In the 1950s, nuclear weapons were tested in the

Pacific Ocean. Although the strength of gamma radiation decreases over time,

this still contributes about 10 units a year to our dose.

Although we cannot measure the dose each person get, members of the public

should not receive a dose of more than 5000 units in one year. There are higher

limits for workers in the nuclear industry up to 50,000 units in one year.

source

dose

per

year

notes

radon and thoron gas higher dose in Cornwall

300

airline pilots receive more

140

decreases over time

total dose for average person

maximum dose for member of public

50,000



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Check what youve learntThe questions below cover all the things you should have learnt in lessons 8 -

12.

See how many questions you can answer from memory then read over your

notes and correct any answers you got wrong or missed out.

1. Complete this sentence.

X-rays are ______________ to the naked eye.

2. Why are X-rays dangerous?

3. Write down two materials that X-rays can pass through.

4. Write down one medical use for X-rays.

5. Write down one use of X-rays in industry.

6. Name the three types of radioactivity.

7. Which types of radioactivity can pass through paper?

8. What substance is used to absorb gamma radiation?



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9. Why are gamma rays dangerous?

10. Describe a medical use for gamma rays.

11. What is a tracer?

12. Describe a non-medical use for gamma radiation.

13. Name three sources of background radiation.

14. Why does an airline pilot get a bigger dose of background radiation than

you do?

15. Translate this sentence.

.

My score out of 15: ____



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Unit 4: Radiations Infrared Lesson 13

Detecting heatYou dont need your eyes to tell you when an electric fire is on

in a room. Your skin particularly the skin on your face

detects the heat given off.

This is because all hot objects give off heat rays orinfrared radiation.

Infrared radiation is invisible to the naked eye. Infrared radiation is also called heat radiation.Measuring infrared

Although you can detect infrared with your skin, scientists prefer more precisemethods. In this experiment, you can use an infrared detector to measure the

heat radiation being given off by a hot object.

What to do

Place the infrared detector at different distances from the heat source. Be

careful. Record the reading on the meter at different distances from the heat

source in the table below.


distance from heat

source (cm)reading on meter

5

10

15

20

25

30

35

40

45

50

meter

0.43

heat source

detector

ruler

50


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Unit 4: Radiations Infrared Lesson 13

Use your results to plot a graph. Remember:

label the axes, including units

put the distance from heat source measurements on the horizontal axis

give your graph a title

Title: ______________________

Questions

1. What was the highest value of infrared you measured?

2. What happened to the infrared measurement as the distance from the heat

source increased?



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Unit 4: Radiations Using infrared Lesson 13: extra

Night visionYou cant see someone in the dark. But if you use the right equipment, you can

see the heat they give off. Night vision equipment detects the infrared radiation

given off by warm objects, and convert it to a picture. Night sights are used bysoldiers to detect the enemy at night. The police use night

vision cameras to follow suspects in the dark. Firefighters

use similar cameras to find people in smoke-filled houses.

The picture on the left shows the sort of thing a firefighter

might see.

Fault-finding and analysisMany objects will start to heat up just before they fail

such as fuses and wires. A thermal camera takes apicture of the heat radiation being given off. This helps

us to spot problems that we wouldnt otherwise notice.

In this picture, the wire on the right has started to heat up

due to a fault in the circuit.

This picture shows a 747 at take-off. The light areas

show where the temperature is greatest the tyres show

up as being very hot. This sort of picture helps aircraft

designers to design parts that can withstand hightemperatures.

ThermogramsThe temperature of the human body varies a lot. The end of your nose is quite

cold your cheeks are much warmer. A thermogram shows the different

temperatures of the body as different colours. Doctors can use thermograms to

identify certain problems. A tumour in the body tends to be hotter than the tissue

around it.

If the blood supply to part of the body is poor, that part wil be coolerthan mormal.

This thermogram doesnt show up too well in black

and white, but you can see how the cheeks and lips

are darker that the nose. The hair and glasses give

off no heat, and appear black.



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Unit 4: Radiations Using infrared Lesson 13: extra

Questions1. Name three jobs where you might use night vision equipment.

2. Look at the picture that a firefighter might see. What do you think it

shows?

3. Look at the picture of the three wires. How can you tell which wire is

heating up?

4. Why are the tyres of the 747 so hot? What has caused this?

5. Look at the picture of the 747. What are the long white streaks at the left

of the picture?

6. Describe two medical problems that can show up on a thermogram.

7. What do you think this medical thermogram shows?



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Unit 4: Radiations Absorbing infrared Lesson 14

Getting through?You know that light can pass through some substances, but is blocked by others.

X-rays and gamma rays can pass through most things. How about infrared?

In this experiment, youll find out whether infrared is absorbed by different

materials.

What to do

1. Set up an infrared detector, a meter and a heat source like this.

2. Write down the meter reading in the table below.

3. Without moving the detector or the heat source, place different materials

between the detector and the heat source. Write down the meter reading

for each material in the table below.

4. Use your results to draw a bar chart.


material reading on meter

no material

sheet of paperbook

hand

sheet of glass

sheet of perspex

wood

detector

0.43

heat source

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Unit 4: Radiations Absorbing infrared Lesson 14

Title: ______________________

Questions

1. Which material absorbed the least infrared?

2. Which material absorbed the most infrared?

3. Explain why it is warmer in a greenhouse than it is in a shed.



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Unit 4: Radiations Absorbing infrared Lesson 14: extra

Infrared and footballSolve the clues to fill in the missing words. Then answer the questions.

One of the most common ________ (1) in football is bruised or sore__________ (2). These sorts of injuries dont usually threaten a players career,

but they can keep him out of a _______(3). If youve ever had a _____ (4) leg,

youll know just how difficult it can be to use badly bruised muscles.

Its vital that players can ________(5) quickly from these injuries which is

where infrared comes in. Theres not a football _____ (6) in the country now

that doesnt have an infrared lamp as part of its treatment room. The ______ (7)

radiation given off by one of these lamps is absorbed by the muscles. This can

help ease the _______ (8) and allows the muscles to recover faster. (If youve

ever used a spray like Deep Heat or Ralgex, youre trying to do the same

thing. However, these sprays use a chemical reaction to produce the heat.)

With intensive ___________ (9) from infrared, a footballer can recover from a

serious dead leg in just a few ______ (10).

Clues

1. A broken leg and a calf strain are both ___________. (8 letters)

2. The biceps and triceps are both _______________. (7 letters)

3. Used to light a fire? (5 letters)4. Not living. (4 letters)

5. Get better. (7 letters)

6. Diamond, Heart, Spade, _____. (4 letters)

7. Anagram of HATE. (4 letters)

8. No _______, no gain. (4 letters)

9. Anagram of NET MATTER. (9 letters)

10. Longer than hours, shorter than weeks. (4 letters)

Questions1. Explain how an infrared lamp can be used to treat a sore leg.

2. Where else might an infrared lamp be used for medical treatment?



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Unit 4: Radiations UV - ultraviolet Lesson 15

UV showing you upClubs and discos often use ultraviolet lights. If youre wearing a clean white

shirt, youll know if youre standing near one of them you seem to glow in the

dark.

Ultraviolet is another type of radiation. Like infrared:

Ultraviolet radiation is invisible to the naked eye.So if ultraviolet is invisible, how does it light up a white shirt?

Using UV

Use the ultraviolet lamp to look at the different objects youve been given.

Look at any white clothing you have on. Look at someone elses teeth.

Dont put the lamp next to your eyes.

Write a sentence about each object you look at.

1

2

3

4

5

6

7



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Unit 4: Radiations UV - ultraviolet Lesson 15

How do you see UV?Our eyes cannot detect ultraviolet light. However:

Some chemicals glow (or fluoresce) when they absorb ultravioletlight.

You can use a security marker to write your address on valuable items say a

mobile phone. The ink in the pen contains a chemical that glows under UV light.

A thief wont be able to see it in daylight, but if the police shine UV light on the

phone, your address will show up clearly.

Most washing powders have a chemical added to them that glows in UV light.

Because sunlight contains some UV, this makes white clothes seem extra cleanand bright when theyre in sunshine. But if you put these clothes under a strong

UV light, they really stand out.

You may have had banknotes checked when youre shopping. Real 10, 20 and

50 notes have a security marking in the paper that glows under UV light. Most

forged notes dont have this chemical. A shop assistant can put your note under

a UV light and quickly check if its genuine.

Questions

1. Describe carefully how we see ultraviolet light.

2. Why do manufacturers add chemicals that glow under UV light to

washing powder?

3. Describe how UV light can be used to identify security markings.



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Unit 4: Radiations The electromagnetic spectrum Lesson 15: extra

Wavelength shortest longest

Name of radiation

Detected by

Medical use

Non-medical use



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Unit 4: Radiations Ultraviolet and medicine Lesson 16

Sunshine sorts the spotsSpots oracne vulgaris to give it its full name is something most teenagers

suffer from at some time. However, for some people, acne is a lot worse than a

few pimples. Very bad acne can lead to severe scarring all over the body.

You may have noticed that you get fewer spots in summer. Thats because the

ultraviolet light in sunshine helps your skin to stay in better condition. People

with very serious acne can use ultraviolet lamps to help keep their skin healthy.

and sunshine shrivels the skinThe ultraviolet radiation in sunlight gives you a tan but thats not all.

Too much exposure to the ultraviolet radiation in sunlightseriously increases your risk of skin cancer.

Scots people, who tend to have very fair skin, are particularly at risk.

and sunshine strengthens the bonesYour body need vitamins to stay healthy. You get vitamin D from all sorts of

foods, including margarine and butter. However, your body also makes vitamin

D if the skin is exposed to a reasonable amount of sunlight. A lack of vitamin D

leads to a disease called rickets, where the bones fail to grow properly. Manychildren in Glasgow suffered from rickets in the early 1900s.

Questions

1. Describe one medical use for ultraviolet radiation.

2. How should people reduce the risk of skin cancer?

3. Why do you think Glasgow children didnt get enough sunlight?



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9. Name three things that show up well under ultraviolet light.

10. Explain why some chemicals show up under ultraviolet light.

11. Explain how ultraviolet light could be used in a bank.

12. Describe a medical use for ultraviolet light.

13. How can you reduce the risk of developing skin cancer?

14. Why are some Scottish people more likely to develop skin cancer?

15. Infrared, ultraviolet, light, X-rays and gamma all travel at the same speed.

What is that speed?

16. Arrange the 5 radiations mentioned in question 15 in order of wavelength

shortest wavelength first.

radiations unit - lessons

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