Theme 3 – Nature of Waves · PDF fileFrequency and Periodic Time are related by a simple formula: f = 1 T ... Since the sounds are travelling at about the same ... Unit 1 – Theme

Form 4 ndash Unit 1 ndash Theme 3 ndash Nature of Waves

1

Theme 3 ndash Nature of Waves

All Waves transfer energy from one place to another They do

this by vibrating something up and down or back and forth

Two different types of waves

There are two types of wave motion transverse and

longitudinal

Transverse Waves

In this kind of wave the direction of wave motion is at 90deg to

the direction of travel Most waves are transverse Here is a

list of transverse waves

all electromagnetic waves

ie radio micro infra red light ultra violet X-rays and

gamma waves

water waves - ripples on the surface of a sea or lake

waves along a rope

Describing waves

An oscillation is a complete to-and-fro movement One

complete cycle

Amplitude Amplitude is the maximum displacement of a

wave from the rest position


2

Periodic Time This is the time taken to perform one

oscillation

Wavelength wavelength is the distance between two crests

(or troughs) or the distance of one cycle Wavelength is given

the symbol (Greek lambda pronounced lam-der)

and is measured in metres because it is a distance

Frequency This is the number of oscillations in one second

Measured in hertz (Hz)

1 kilohertz = 1 kHz = 1000 Hz 1 megahertz = 1 MHz = 1000000 Hz

1 gigahertz = 1 GHz = 1000000000 Hz

-distance

Longitudinal Waves

In this kind of wave the direction of wave motion is at 180deg

parallel to the direction of travel The oscillations are in the

same direction as the wave All longitudinal waves are

mechanical waves They need a material to travel in they

cannot travel in a vacuum

Examples of longitudinal waves are

Sound ultrasound and earthquake P-waves


3

The features of a longitudinal wave are

Compression - area of high pressure

Rarefaction - area of low pressure

Wavelength - distance between two compressions or two

rarefactions

Frequency and Periodic Time are related by a simple formula

f = 1

T

The Wave Equation

All waves whether longitudinal or transverse obey the wave

equation

Wave speed (ms) = frequency (Hz) times wavelength (m)

In Physics code

Here are a few wave speeds

Electromagnetic waves in a vacuum - 3 times 108 ms

Electromagnetic waves in glass - 2 times 108 ms

Sound in steel - 6000 ms

Sound in water - 1500 ms Sound in air - 340 ms

Speed Frequency amp Wavelength

The frequency of waves is set at the source itself For instance if John pokes a pond with a stick twice each second

the frequency will be 2 Hz


4

As the waves travel over the ponds surface this frequency

will not change What may change is the distance between

waves - the wavelength - and their speed

Water waves

Progressive Waves - Waves that travel or propagate from a

source are called progressive waves An obvious example is

the ripples on a pond when you throw a stone into the water

Both longitudinal and transverse waves can travel through

water

Longitudinal waves travel through water underneath the surface This is under water sound and can be used by

sea creatures to communicate (whales dolphins etc)

and by boats for echo location

Transverse waves travel on the water

surface and these are the waves which

we see as they make the surface go up

and down Transverse water waves are

shown as a series of parallel lines

These lines represent the peaks of the

wave as you are looking down on it

from above

Reflection Refraction and Diffraction

The wavelength is the distance between two peaks or the

distance between two troughs

Water waves are reflected from hard flat surfaces as shown

below

After reflection a wave has

the same speed frequency and wavelength it is only

the direction of the wave

that has changed


5

Water waves travel faster on the surface of deep water than

they do on shallow water The change in speed of the wave will

cause refraction

The slower wave in the shallow water has a smaller

wavelength The amount of refraction increases as the change

in speed increases

Waves Diffraction

Diffraction occurs when the wavelength of a wave

is of a similar size to an obstacle or a gap in a barrier

After diffraction a wave will have the same speed frequency

and wavelength

Electromagnetic waves have a huge range of wavelengths

Radio waves can diffract around hills mountains or even the

whole planet Light waves can diffract through tiny slits

X-rays can diffract around atoms

Water waves can diffract when passing through a gap in a

harbour wall

The wavelength of water waves

may be several metres

If the wavelength is of a similar

size to a gap in a harbour wall

then the wave will diffract as

shown below


6

If the wavelength does not match

the size of the gap

then only a little diffraction will

occur at the edge of the wave The part of the wave which hits the wall

in the above two pictures is

reflected straight back on itself

Sound

Sound is always produced by

something vibrating The

vibrations will make matter -

either solid liquid or gas - near it vibrate In this way energy is

taken away from the source of the

vibrations The amplitude of the

wave determines the volume of a

sound

We call these vibrations sound Our ears pick them up and tell

our brain what we can hear The vibrations are longitudinal

Bell Jar Experiment

With the bell ringing continuously inside it can be easily heard outside of the jar Once a

vacuum pump is turned on the air is slowly

removed As this happens the sound gets

quieter until eventually it cannot be heard at

all

Inside the bell jar the bell can still be seen to

ring If the rubber bands hanging it are good

enough few vibrations will pass up them to the glass (to be

heard) Letting the air back in allows the sound to be heard

again

Sounds cannot travel through a vacuum


7

Speed Of Sound

Sound waves are vibrations which cannot travel through

a vacuum - the total absence of matter The more matter

there is and the closer atoms are together the easier it is for

sound can travel

In air which is a mixture of gases the speed of sound is

around 340 ms depending on air temperature For water the

molecules are much closer together so vibrations pass much

more quickly between them As a result sound can travel at

around 1500 ms In solids where atoms are really close

together and very tightly attached to each other the speed of

sound is even higher - typically 5000 ms

Ultasound

This consist of sound that is above the range of human

hearing It even travels at exactly the same speed as sound in

any medium Humans can hear sound within the frequency

range of about 20 to 20000 Hz so any sound above 20 kHz is

ultrasound Uses ndash

1 Unborn babies can be photographed to check its size - and

even if there is more than one Its use in scanning goes far

beyond pregnancies Many other parts of the body are

analysed using it (bladder gallstones the heart etc) but it

doesnt even stop there Aeroplane wings can be checked for cracks that would be invisible on the surface

2 Ultrasound Treatments to clean things In fact really dirty

teeth can be cleaned superbly in this way Really delicate

mechanisms - such as in antique clocks and watches - can

also be safely cleaned

3 Ships use in Ultrasound and SONAR to detect fish sea

bottom


8

A ship sends a pulse of ultrasound

and receives an echo 0middot3 seconds

later If the speed of sound in water

is 1500 ms calculate its depth

speed = distance time

distance = speed times time

distance = 1500 times 0middot3 = 450 m

BUT this is the total distance travelled by the sound - so the

depth is half of this

Depth = 450 2 = 225 m

4 Used by animals to communicate ndash BatsDolphins

Any sound that you hear as a tone is made of regular evenly spaced waves of air molecules The most noticeable difference

between various tonal sounds is that some sound higher or

lower than others These differences in the pitch of the sound

are caused by different spacing in the waves that is different

frequency

Since the sounds are travelling at about the same speed the

one with the shorter wavelength will go by more frequently it

has a higher frequency or pitch In other words it sounds

higher


9

The amplitude of the wave determines the loudness of the

sound

The amplitude of sound waves is

measured in decibels Leaves

rustling in the wind are about 10

decibels a jet engine is about 120

decibels

Amplitude is Loudness

THEME 3 - OPTICS

The only special thing about light is that our eyes can detect it

However it is just a tiny part of a collection of electromagnetic

waves that make up the electromagnetic spectrum

The objects which we see can be placed into one of two

categories luminous objects and non luminous objects

Luminous objects are objects which generate their own light

Eg sun electric bulb

Non Luminous objects are objects which are capable of

reflecting light to our eyes Eg moon grass sky

Without light there would be no sight


10

Light is a transverse wave It is one part (region) of the

electromagnetic spectrum Light is the visible region it is

the part used by our eyes to see Like any electromagnetic

wave light can travel through a vacuum Light travels through

the vacuum of space from the Sun to the Earth

Light travels very quickly There is nothing which can travel

faster The speed of light is 300000000 ms

(that is 300 million metres per second - not easy to imagine)

Reflection - ( Bouncing of light)

Any type of wave can be reflected Reflection best occurs from

flat hard surfaces After reflection a wave has the same

speed frequency and wavelength it is only the direction of the

wave that has changed

For light (and other electromagnetic radiation) a flat shiny

surface like a plane mirror is a good reflector

A plane mirror is one

which is straight and not

curved

The light ray which hits

the mirror is called the

incident ray The light ray which

bounces off the mirror is

called the reflected ray The angle of incidence equals the

angle of reflection i = r This means that whatever angle the light ray hits the mirror it will be reflected off at the same

angle

If the surface of the mirror is not smooth but rough or bumpy

then light will be reflected at many different angles The image

in the mirror will be blurred and unclear This is called diffuse

reflection When you look into a mirror you see a reflection

which is an image of the real object


11

The image appears to be the

same distance behind the

mirror as the real object is in front of it

This is because the brain

thinks that light travels in

straight lines without changing

direction

The image is called virtual

because it does not really

exist behind the mirror The

virtual image is the same size as the object but with left and

right reversed ( laterally inverted)

Refraction ( bending of light)

Any type of wave can be refracted which means a change of

direction Refraction can occur when the speed of a wave

changes as it moves from one medium to another

After refraction the wave has the same frequency

but a different speed wavelength and direction

When a wave enters a new medium its change in speed will

also change its wavelength If the wave enters the new

medium at any angle other than normal to the boundary then

the change in the waves speed will also change its direction

A material is transparent if you can see through it If you can

see through it it means that light can travel through it

Transparent materials include air glass Perspex and water

Light travels at different speeds in different materials because

they have different densities The higher the density the

slower light travels Light travels fastest in space (a vacuum)

and a little slower in air Light moves noticeably more slowly in

glass than in air because glass is obviously more dense


12

A line drawn at right

angles to the

boundary between the

two media (air and

glass) is called a

normal

Light which enters a glass block along a normal (at 90 degrees) does not change direction but it does travel more slowly

through the glass When a ray of light enters a glass block at

an angle other than the normal it changes speed wavelength

and direction as shown below

Conditions of Refraction

The angle i is called the angle of incidence while

angle r is called angle of

refraction The light must

change speed when

crossing the boundary

In going from a less dense medium (air) to a more dense

medium (glass) light bends towards the normalThis means

that i gt r (the angle i is greater than the angle r)

In going from a more dense to a less dense medium (glass to

air) light bends away from the normal How much the light

bends depends on its colour

The change in angle of the light ray is the same when it enters

and leaves the glass If the incident ray had continued without

changing direction then the emergent ray would be parallel to

it Like any wave the speed of a light wave is dependent

upon the properties of the medium


13

Refractive Index - n

Index of refraction values (represented by the symbol n) are

numerical index values which are expressed relative to the

speed of light in a vacuum The index of refraction value of a

material is a number which indicates the number of times

slower that a light wave would be in that material than it is in a

vacuum

ή = Speed of light in air

Speed of light in medium

Material Index of Refraction

Vacuum 100

Water 133

Glass 150

Diamond 240

The index of refraction values thus provide a measure of the

relative speed of a light wave in a particular medium

Real and Apparent Depth

To an observer standing at

the side of a swimming pool

objects under the water

appear to be nearer the

surface than they really are


14

A fish appears to be nearer to

the surface than it really is

A straight stick appears to be

bent when part in and part

out of water

Both these effects are caused by

refraction of light at the surface of the water Therefore this

effect is related to the refractive

index of the media involved

The real depth of the fish is R and its apparent depth is A It is

clear that n represents the refractive index of light going from

air to water we have

Refractive index n = Real Depth Apparent depth

When light emerges from glass or water into air it speeds up

again As it meets the glass-air boundary at any angle greater than 0o it will refract away from the normal If you look at a

stick that is poking into some water at an angle the stick looks

bent because of refraction The bottom of the stick seems to be

nearer the surface of the water than it really is It also explains

why flat-based swimming pools appear to get shallower as you

look towards the end furthest from you

Total Internal Reflection - Critical Angle

When a light ray emerges from glass into air it is refracted and bends away from the normal so i lt r As i is made bigger the

refracted ray gets closer and closer to the surface of the glass

When the refracted ray is just touching the glass surface that is angle r = 90 degrees than angle i is called the critical

angle


15

The critical angle is different for different materials for glass it is about 42 degrees Total internal reflection happens when i is

bigger than the critical angleWhen a light ray tries to move

from glass to air at an angle greater than the critical angle the

refracted ray cannot escape from the glass and total internal

reflection occurs

Refraction cannot happen and all

of the light is reflected

at the glass air boundary as if it

had hit a mirror i = r

It is called internal reflection

because it occurs inside the glass

and total because all the light must

be reflected

Total Internal Reflection (TIR) can occur in prisms and optical

fibres

Total Internal Reflection - Prisms

A right angle prism can be used to

change the direction of a light ray by

90 degrees or 180 degrees

The light ray enters along a normal

and continues straight on until it hits

the back face of the prism Total


16

internal reflection occurs here because light strikes the surface

at 45 degrees which is greater than the critical angle

The light ray then emerges from the

prism along a normal and so continues

straight through This type of prism

can be used in a periscope Two right

angle prisms can be used to form a periscope as shown below Total

internal reflection occurs at the back

face of the prisms

A periscope may be used by people

(i) in a submarine to see above the

sea surface

(ii) to see over the heads of people in a crowd

A right angle prism can be used to change

the direction of light by 180

degrees as shown below

The same effect can result from two prisms arranged as shown

belowEither of these arrangements may be used in

binoculars or reflectors on the rear of cars and bicycles


17

Optical fibres

An optical fibre is a long thin strand of glass which has an outer

plastic coating

Light from a laser enters at one end of the fibre striking the

surface of the glass at an angle greater than the critical

angle Total internal reflection occurs at the glass surface

and the light cannot escape until it reaches the other end of the

fibre The plastic coating prevents the glass surface from

getting scratched which might allow the light to escape

through the side of the fibre

Optical fibres are used in endoscopes and for

telecommunications

Telecommunications

Information is transmitted (sent) using electromagnetic waves

light in optical fibres This information can be used in many

ways including telephone television fax and internet

A digital signal has a higher quality than an analogue signal

An endoscope is an instrument used by Doctors and

Surgeons A bundle of very thin optical fibres is used with

lenses to see inside a body


18

Dispersion of Light

A glass prism of angle 60 degrees can

disperse white light

into its different colours (called a

spectrum)

The seven colours of light are

Red Orange Yellow Green Blue Indigo and violet

Different colours of light have each a different frequency and wavelength The different colours are refracted by different

amounts Red light has the longest wavelength and is

refracted least Violet light has the shortest wavelength and is

refracted most

The source of light may

also emit infra-red and

ultraviolet light

Infra-red light is heat

radiation with a longer wavelength than red light A

thermometer placed at IR will show a rise in temperature Ultraviolet light has a shorter wavelength than violet light A

fluorescent material will glow when placed at UV

Lenses

A lens is a carefully ground or molded piece of transparent material which refracts light rays in such as way as to form an

image

First consider a convex lens Suppose that several rays of

light approach the lens and suppose that these rays of light

are traveling parallel to the principal axis (The line that passes

from the optical centre the centre of the lens)


19

Upon reaching the front face of the lens each ray of light will

refract towards the normal to the surface Once the light ray

refracts across the boundary and enters the lens it travels in a

straight line until it reaches the back face of the lens At this

boundary each ray of light will refract away from the normal to

the surface it will bend away from the normal line

The principal focus is that point on the principal axis through

which all rays pass after passing through the lens

Refraction for Diverging Lenses (concave lens)

The incident rays diverge upon refracting through the lens For

this reason a concave lens can never produce a real image

Concave lenses produce images which are virtual


20

Refraction Rules for a Converging Lens

There are three rules of refraction for converging lenses by

which we can predict the formation of an image

1 Any incident ray traveling

parallel to the principal axis

of a converging lens will refract through the lens and

travel through the focal point

on the opposite side of the

lens

2 Any incident ray traveling through the focal point on

the way to the lens will

refract through the lens

and travel parallel to

the principal

axis

3 An incident ray which passes through

the center of the lens will in affect

continue in the same direction that it

had when it entered the lens

Converging Lenses - Ray Diagrams

Step-by-Step Method for Drawing Ray

Diagrams

The method of drawing ray diagrams for

a convex lens is described below

1 Pick a point on the top of the object

and draw three incident rays traveling

towards the lens


21

Using a straight edge accurately draw one ray so that it passes

exactly through the focal point on the way to the lens Draw

the second ray such that it travels exactly parallel to the

principal axis Draw the third incident ray such that it travels

directly to the exact center of the lens Place arrowheads upon the rays to indicate their direction of travel

2 Once these incident rays strike the lens refract them

according to the three rules of refraction for converging lenses

3 Mark the image of the top of the object

The image point of the top of the object is the point where the

three refracted rays intersect If the object is a vertical line

then the image is also a vertical line and its bottom is located

upon the principal axis

Converging Lenses - Object-Image Relations

Case 1 The object is located beyond 2F

When the object is located beyond the 2F point the

image will always be located

somewhere in between the 2F

point and the focal point (F)

on the other side of the lens In this case the image will be an

inverted image That is to say the image is upside down In this case the image is reduced in size in other words the

image dimensions are smaller than the object dimensions

Finally the image is a real image

Case 2 The object is located at 2F

When the object is located at the

2F point the image will also be

located at the 2F point on the other side of the lens In this case the


22

image will be inverted The image dimensions are equal to

the object dimensions Finally the image is a real image

Case 3 The object is located between 2F and F

In this case the image will be inverted (ie a right-side-up object

results in an upside-down image)

The image dimensions are larger than

the object dimensions(Magnified)


Case 4 The object is located at F


focal point no image is formed After

refracting the light rays are traveling parallel to each other and cannot

produce an image

Case 5 The object is located

in front of F

When the object is located at a location in front of the focal

point the image will always be

located somewhere on the same side of the lens as the object

The image is located behind the object In this case the image

will be an upright image That is to say if the object is right-

side up then the image will also be right-side up In this case

the image is magnified Finally the image is a virtual image

Light rays diverge upon refraction for this reason the image location can only be found by extending the refracted rays

backwards on the objects side the lens


23

Object at Image at Size Orientation Nature Use

Infinity F Diminished Inverted Real Image on a

film (at infinity)

gt2F Between F

and 2F Diminished Inverted Real

Image on a film

(close up)

2F 2F Same size Inverted Real Photocopier

Between 2F and F

gt2F Magnified Inverted Real Projector

F Infinity Magnified Inverted Real Spot light

ltF ltF (on same

side) Magnified Upright Virtual

Magnifying glass

Magnification

The magnification is the ratio of the height of the object to

the height of the image If the magnification is greater than 1 than the image is greater than object (magnified) If the

magnification is a number with an absolute value less than 1

than the image is smaller than object (diminished)

Magnification = height of image = image distance

height of object object distance

The Electromagnetic and Visible Spectra

Electromagnetic waves are waves which are capable of traveling through a vacuum unlike mechanical waves which

require a medium

Electromagnetic waves exist with an enormous range of

frequencies This continuous range of frequencies is known as

the electromagnetic spectrum The longer wavelength

lower frequency regions are located on the far right of the

spectrum and the shorter wavelength higher frequency regions

are on the far left


24

Remember also that its the high frequency waves that are the

most dangerous (Gamma rays)

All electro-magnetic waves travel in a straight line

Electromagnetic waves are transverse waves which have

both an electric and a magnetic effect All electromagnetic waves travel at the same speed (in a

vacuum)

Electromagnetic waves travel very quicklyThere is

nothing which can travel faster Their speed is

300000000 ms in a vacuum

They can have a wide variety of wavelengths and

frequencies which form the electromagnetic spectrum

Radio Waves

These are the longest of all the electro-magnetic waves and are used in telecommunications (radio and TV broadcasts as

well as portable phones and walkie talkies)

Microwaves

These are really just very short radio waves and are very

useful in communications Uses


25

Satellite Dishes - Microwaves are used to transmit

television signals to satellites in orbit microwaves are also

able to travel through the atmosphere This means we can

transmit signals back to the ground

Microwave Ovens - Microwave ovens also use microwaves as

they can be tuned (all microwaves use a frequency of 2450

MHz no matter what their power) to match the vibrations of

water molecules The waves just make the molecules vibrate

with a larger amplitude which heats the food up

Microwaves in Cars - Microwaves reflect well off metal

objects - this fact is put to good use in speed guns and speed

traps Some cars are fitted with low power microwave emitters

at the back to help drivers park safely

Infra Red

Beyond the red end of the visible spectrum is infra red This is

detectable by our skin as heat radiation

A filament lamp emits light and infra red radiation (heat

radiation) We can see the red light and feel the warmth on

our skin

The sun also emits huge amounts of infra-red radiation It is

this that keeps the Earth warm and can also heat our homes

for free

Visible Light

There are many millions of colours which we can distinguish with our eyes Each colour of light we see has a different

wavelength (and frequency) The longest wavelength light we

can see is red at about 700 nm (700 times 10-9 m) Any longer

than this and we cannot see it The shortest wavelength light

we can see is violet at about 400 nm (400 times 10-9 m) Any

shorter than this and we see nothing


26

Ultra Violet

Beyond violet is a dangerous type of radiation called ultra violet UV is also emited from the Sun It is to this that our

bodies respond when out in the sunshine for too long

A brown pigment is produced in the skin to help protect our

living cells from destruction - or even cancer UV is partly

absorbed by the ozone layer but it is still important to apply

sunscreen as an extra layer of protection

X-Rays

An X-ray photograph is taken to examine broken bone or of the teeth X-rays are even more dangerous than UV but are

amazingly useful X-rays are absorbed by bone but pass

almost perfectly through flesh

Gamma Waves

These are the most dangerous and penetrating form of electro-

magnetic waves Gamma rays are emitted by some radioactive

nuclei so have to be stored in lead-lined boxes

Gamma waves have the shortest wavelengths and highest

frequency They are also produced during supernova

explosions Despite the apparent danger they can be amazingly useful Amongst others they are widely used in

hospitals Some medical imaging equipment involves the use of

gamma rays Gamma waves can also be used to kill cancerous

cells by direct exposure


2

Periodic Time This is the time taken to perform one

oscillation

Wavelength wavelength is the distance between two crests

(or troughs) or the distance of one cycle Wavelength is given

the symbol (Greek lambda pronounced lam-der)

and is measured in metres because it is a distance

Frequency This is the number of oscillations in one second

Measured in hertz (Hz)

1 kilohertz = 1 kHz = 1000 Hz 1 megahertz = 1 MHz = 1000000 Hz

1 gigahertz = 1 GHz = 1000000000 Hz

-distance

Longitudinal Waves

In this kind of wave the direction of wave motion is at 180deg

parallel to the direction of travel The oscillations are in the

same direction as the wave All longitudinal waves are

mechanical waves They need a material to travel in they

cannot travel in a vacuum

Examples of longitudinal waves are

Sound ultrasound and earthquake P-waves


3





rarefactions


f = 1

T

The Wave Equation


equation


In Physics code










4




Water waves





water











from above





below




that has changed


5



cause refraction



in speed increases

Waves Diffraction




and wavelength






harbour wall






shown below


6


the size of the gap





Sound








sound



Bell Jar Experiment





all





again



7

Speed Of Sound




sound can travel








Ultasound
















bottom


8










Depth = 450 2 = 225 m






frequency




higher


9


sound





decibels


THEME 3 - OPTICS












10


















curved







angle







11







direction

























12


angles to the


two media (air and

glass) is called a

normal









change speed when














13







vacuum




Vacuum 100

Water 133

Glass 150

Diamond 240










14





out of water




















angle


15





reflection occurs








be reflected


fibres









16









face of the prisms



sea surface









17

Optical fibres


plastic coating









telecommunications

Telecommunications









18

Dispersion of Light




spectrum)






refracted most



ultraviolet light





Lenses


image






19














20









lens





the principal

axis







Diagrams





towards the lens


21




























22













produce an image


in front of F











23



film (at infinity)

gt2F Between F


Image on a film

(close up)


Between 2F and F



ltF ltF (on same


Magnifying glass

Magnification









require a medium






are on the far left


24






vacuum)






Radio Waves



Microwaves




25














Infra Red





our skin



for free

Visible Light








26

Ultra Violet







X-Rays




Gamma Waves











3





rarefactions


f = 1

T

The Wave Equation


equation


In Physics code










4




Water waves





water











from above





below




that has changed


5



cause refraction



in speed increases

Waves Diffraction




and wavelength






harbour wall






shown below


6


the size of the gap





Sound








sound



Bell Jar Experiment





all





again



7

Speed Of Sound




sound can travel








Ultasound
















bottom


8










Depth = 450 2 = 225 m






frequency




higher


9


sound





decibels


THEME 3 - OPTICS












10


















curved







angle







11







direction

























12


angles to the


two media (air and

glass) is called a

normal









change speed when














13







vacuum




Vacuum 100

Water 133

Glass 150

Diamond 240










14





out of water




















angle


15





reflection occurs








be reflected


fibres









16









face of the prisms



sea surface









17

Optical fibres


plastic coating









telecommunications

Telecommunications









18

Dispersion of Light




spectrum)






refracted most



ultraviolet light





Lenses


image






19














20









lens





the principal

axis







Diagrams





towards the lens


21




























22













produce an image


in front of F











23



film (at infinity)

gt2F Between F


Image on a film

(close up)


Between 2F and F



ltF ltF (on same


Magnifying glass

Magnification









require a medium






are on the far left


24






vacuum)






Radio Waves



Microwaves




25














Infra Red





our skin



for free

Visible Light








26

Ultra Violet







X-Rays




Gamma Waves











4




Water waves





water











from above





below




that has changed


5



cause refraction



in speed increases

Waves Diffraction




and wavelength






harbour wall






shown below


6


the size of the gap





Sound








sound



Bell Jar Experiment





all





again



7

Speed Of Sound




sound can travel








Ultasound
















bottom


8










Depth = 450 2 = 225 m






frequency




higher


9


sound





decibels


THEME 3 - OPTICS












10


















curved







angle







11







direction

























12


angles to the


two media (air and

glass) is called a

normal









change speed when














13







vacuum




Vacuum 100

Water 133

Glass 150

Diamond 240










14





out of water




















angle


15





reflection occurs








be reflected


fibres









16









face of the prisms



sea surface









17

Optical fibres


plastic coating









telecommunications

Telecommunications









18

Dispersion of Light




spectrum)






refracted most



ultraviolet light





Lenses


image






19














20









lens





the principal

axis







Diagrams





towards the lens


21




























22













produce an image


in front of F











23



film (at infinity)

gt2F Between F


Image on a film

(close up)


Between 2F and F



ltF ltF (on same


Magnifying glass

Magnification









require a medium






are on the far left


24






vacuum)






Radio Waves



Microwaves




25














Infra Red





our skin



for free

Visible Light








26

Ultra Violet







X-Rays




Gamma Waves











5



cause refraction



in speed increases

Waves Diffraction




and wavelength






harbour wall






shown below


6


the size of the gap





Sound








sound



Bell Jar Experiment





all





again



7

Speed Of Sound




sound can travel








Ultasound
















bottom


8










Depth = 450 2 = 225 m






frequency




higher


9


sound





decibels


THEME 3 - OPTICS












10


















curved







angle







11







direction

























12


angles to the


two media (air and

glass) is called a

normal









change speed when














13







vacuum




Vacuum 100

Water 133

Glass 150

Diamond 240










14





out of water




















angle


15





reflection occurs








be reflected


fibres









16









face of the prisms



sea surface









17

Optical fibres


plastic coating









telecommunications

Telecommunications









18

Dispersion of Light




spectrum)






refracted most



ultraviolet light





Lenses


image






19














20









lens





the principal

axis







Diagrams





towards the lens


21




























22













produce an image


in front of F











23



film (at infinity)

gt2F Between F


Image on a film

(close up)


Between 2F and F



ltF ltF (on same


Magnifying glass

Magnification









require a medium






are on the far left


24






vacuum)






Radio Waves



Microwaves




25














Infra Red





our skin



for free

Visible Light








26

Ultra Violet







X-Rays




Gamma Waves











6


the size of the gap





Sound








sound



Bell Jar Experiment





all





again



7

Speed Of Sound




sound can travel








Ultasound
















bottom


8










Depth = 450 2 = 225 m






frequency




higher


9


sound





decibels


THEME 3 - OPTICS












10


















curved







angle







11







direction

























12


angles to the


two media (air and

glass) is called a

normal









change speed when














13







vacuum




Vacuum 100

Water 133

Glass 150

Diamond 240










14





out of water




















angle


15





reflection occurs








be reflected


fibres









16









face of the prisms



sea surface









17

Optical fibres


plastic coating









telecommunications

Telecommunications









18

Dispersion of Light




spectrum)






refracted most



ultraviolet light





Lenses


image






19














20









lens





the principal

axis







Diagrams





towards the lens


21




























22













produce an image


in front of F











23



film (at infinity)

gt2F Between F


Image on a film

(close up)


Between 2F and F



ltF ltF (on same


Magnifying glass

Magnification









require a medium






are on the far left


24






vacuum)






Radio Waves



Microwaves




25














Infra Red





our skin



for free

Visible Light








26

Ultra Violet







X-Rays




Gamma Waves











7

Speed Of Sound




sound can travel








Ultasound
















bottom


8










Depth = 450 2 = 225 m






frequency




higher


9


sound





decibels


THEME 3 - OPTICS












10


















curved







angle







11







direction

























12


angles to the


two media (air and

glass) is called a

normal









change speed when














13







vacuum




Vacuum 100

Water 133

Glass 150

Diamond 240










14





out of water




















angle


15





reflection occurs








be reflected


fibres









16









face of the prisms



sea surface









17

Optical fibres


plastic coating









telecommunications

Telecommunications









18

Dispersion of Light




spectrum)






refracted most



ultraviolet light





Lenses


image






19














20









lens





the principal

axis







Diagrams





towards the lens


21




























22













produce an image


in front of F











23



film (at infinity)

gt2F Between F


Image on a film

(close up)


Between 2F and F



ltF ltF (on same


Magnifying glass

Magnification









require a medium






are on the far left


24






vacuum)






Radio Waves



Microwaves




25














Infra Red





our skin



for free

Visible Light








26

Ultra Violet







X-Rays




Gamma Waves











8










Depth = 450 2 = 225 m






frequency




higher


9


sound





decibels


THEME 3 - OPTICS












10


















curved







angle







11







direction

























12


angles to the


two media (air and

glass) is called a

normal









change speed when














13







vacuum




Vacuum 100

Water 133

Glass 150

Diamond 240










14





out of water




















angle


15





reflection occurs








be reflected


fibres









16









face of the prisms



sea surface









17

Optical fibres


plastic coating









telecommunications

Telecommunications









18

Dispersion of Light




spectrum)






refracted most



ultraviolet light





Lenses


image






19














20









lens





the principal

axis







Diagrams





towards the lens


21




























22













produce an image


in front of F











23



film (at infinity)

gt2F Between F


Image on a film

(close up)


Between 2F and F



ltF ltF (on same


Magnifying glass

Magnification









require a medium






are on the far left


24






vacuum)






Radio Waves



Microwaves




25














Infra Red





our skin



for free

Visible Light








26

Ultra Violet







X-Rays




Gamma Waves











9


sound





decibels


THEME 3 - OPTICS












10


















curved







angle







11







direction

























12


angles to the


two media (air and

glass) is called a

normal









change speed when














13







vacuum




Vacuum 100

Water 133

Glass 150

Diamond 240










14





out of water




















angle


15





reflection occurs








be reflected


fibres









16









face of the prisms



sea surface









17

Optical fibres


plastic coating









telecommunications

Telecommunications









18

Dispersion of Light




spectrum)






refracted most



ultraviolet light





Lenses


image






19














20









lens





the principal

axis







Diagrams





towards the lens


21




























22













produce an image


in front of F











23



film (at infinity)

gt2F Between F


Image on a film

(close up)


Between 2F and F



ltF ltF (on same


Magnifying glass

Magnification









require a medium






are on the far left


24






vacuum)






Radio Waves



Microwaves




25














Infra Red





our skin



for free

Visible Light








26

Ultra Violet







X-Rays




Gamma Waves











10


















curved







angle







11







direction

























12


angles to the


two media (air and

glass) is called a

normal









change speed when














13







vacuum




Vacuum 100

Water 133

Glass 150

Diamond 240










14





out of water




















angle


15





reflection occurs








be reflected


fibres









16









face of the prisms



sea surface









17

Optical fibres


plastic coating









telecommunications

Telecommunications









18

Dispersion of Light




spectrum)






refracted most



ultraviolet light





Lenses


image






19














20









lens





the principal

axis







Diagrams





towards the lens


21




























22













produce an image


in front of F











23



film (at infinity)

gt2F Between F


Image on a film

(close up)


Between 2F and F



ltF ltF (on same


Magnifying glass

Magnification









require a medium






are on the far left


24






vacuum)






Radio Waves



Microwaves




25














Infra Red





our skin



for free

Visible Light








26

Ultra Violet







X-Rays




Gamma Waves











11







direction

























12


angles to the


two media (air and

glass) is called a

normal









change speed when














13







vacuum




Vacuum 100

Water 133

Glass 150

Diamond 240










14





out of water




















angle


15





reflection occurs








be reflected


fibres









16









face of the prisms



sea surface









17

Optical fibres


plastic coating









telecommunications

Telecommunications









18

Dispersion of Light




spectrum)






refracted most



ultraviolet light





Lenses


image






19














20









lens





the principal

axis







Diagrams





towards the lens


21




























22













produce an image


in front of F











23



film (at infinity)

gt2F Between F


Image on a film

(close up)


Between 2F and F



ltF ltF (on same


Magnifying glass

Magnification









require a medium






are on the far left


24






vacuum)






Radio Waves



Microwaves




25














Infra Red





our skin



for free

Visible Light








26

Ultra Violet







X-Rays




Gamma Waves











12


angles to the


two media (air and

glass) is called a

normal









change speed when














13







vacuum




Vacuum 100

Water 133

Glass 150

Diamond 240










14





out of water




















angle


15





reflection occurs








be reflected


fibres









16









face of the prisms



sea surface









17

Optical fibres


plastic coating









telecommunications

Telecommunications









18

Dispersion of Light




spectrum)






refracted most



ultraviolet light





Lenses


image






19














20









lens





the principal

axis







Diagrams





towards the lens


21




























22













produce an image


in front of F











23



film (at infinity)

gt2F Between F


Image on a film

(close up)


Between 2F and F



ltF ltF (on same


Magnifying glass

Magnification









require a medium






are on the far left


24






vacuum)






Radio Waves



Microwaves




25














Infra Red





our skin



for free

Visible Light








26

Ultra Violet







X-Rays




Gamma Waves











13







vacuum




Vacuum 100

Water 133

Glass 150

Diamond 240










14





out of water




















angle


15





reflection occurs








be reflected


fibres









16









face of the prisms



sea surface









17

Optical fibres


plastic coating









telecommunications

Telecommunications









18

Dispersion of Light




spectrum)






refracted most



ultraviolet light





Lenses


image






19














20









lens





the principal

axis







Diagrams





towards the lens


21




























22













produce an image


in front of F











23



film (at infinity)

gt2F Between F


Image on a film

(close up)


Between 2F and F



ltF ltF (on same


Magnifying glass

Magnification









require a medium






are on the far left


24






vacuum)






Radio Waves



Microwaves




25














Infra Red





our skin



for free

Visible Light








26

Ultra Violet







X-Rays




Gamma Waves











14





out of water




















angle


15





reflection occurs








be reflected


fibres









16









face of the prisms



sea surface









17

Optical fibres


plastic coating









telecommunications

Telecommunications









18

Dispersion of Light




spectrum)






refracted most



ultraviolet light





Lenses


image






19














20









lens





the principal

axis







Diagrams





towards the lens


21




























22













produce an image


in front of F











23



film (at infinity)

gt2F Between F


Image on a film

(close up)


Between 2F and F



ltF ltF (on same


Magnifying glass

Magnification









require a medium






are on the far left


24






vacuum)






Radio Waves



Microwaves




25














Infra Red





our skin



for free

Visible Light








26

Ultra Violet







X-Rays




Gamma Waves











15





reflection occurs








be reflected


fibres









16









face of the prisms



sea surface









17

Optical fibres


plastic coating









telecommunications

Telecommunications









18

Dispersion of Light




spectrum)






refracted most



ultraviolet light





Lenses


image






19














20









lens





the principal

axis







Diagrams





towards the lens


21




























22













produce an image


in front of F











23



film (at infinity)

gt2F Between F


Image on a film

(close up)


Between 2F and F



ltF ltF (on same


Magnifying glass

Magnification









require a medium






are on the far left


24






vacuum)






Radio Waves



Microwaves




25














Infra Red





our skin



for free

Visible Light








26

Ultra Violet







X-Rays




Gamma Waves











16









face of the prisms



sea surface









17

Optical fibres


plastic coating









telecommunications

Telecommunications









18

Dispersion of Light




spectrum)






refracted most



ultraviolet light





Lenses


image






19














20









lens





the principal

axis







Diagrams





towards the lens


21




























22













produce an image


in front of F











23



film (at infinity)

gt2F Between F


Image on a film

(close up)


Between 2F and F



ltF ltF (on same


Magnifying glass

Magnification









require a medium






are on the far left


24






vacuum)






Radio Waves



Microwaves




25














Infra Red





our skin



for free

Visible Light








26

Ultra Violet







X-Rays




Gamma Waves











17

Optical fibres


plastic coating









telecommunications

Telecommunications









18

Dispersion of Light




spectrum)






refracted most



ultraviolet light





Lenses


image






19














20









lens





the principal

axis







Diagrams





towards the lens


21




























22













produce an image


in front of F











23



film (at infinity)

gt2F Between F


Image on a film

(close up)


Between 2F and F



ltF ltF (on same


Magnifying glass

Magnification









require a medium






are on the far left


24






vacuum)






Radio Waves



Microwaves




25














Infra Red





our skin



for free

Visible Light








26

Ultra Violet







X-Rays




Gamma Waves











18

Dispersion of Light




spectrum)






refracted most



ultraviolet light





Lenses


image






19














20









lens





the principal

axis







Diagrams





towards the lens


21




























22













produce an image


in front of F











23



film (at infinity)

gt2F Between F


Image on a film

(close up)


Between 2F and F



ltF ltF (on same


Magnifying glass

Magnification









require a medium






are on the far left


24






vacuum)






Radio Waves



Microwaves




25














Infra Red





our skin



for free

Visible Light








26

Ultra Violet







X-Rays




Gamma Waves











19














20









lens





the principal

axis







Diagrams





towards the lens


21




























22













produce an image


in front of F











23



film (at infinity)

gt2F Between F


Image on a film

(close up)


Between 2F and F



ltF ltF (on same


Magnifying glass

Magnification









require a medium






are on the far left


24






vacuum)






Radio Waves



Microwaves




25














Infra Red





our skin



for free

Visible Light








26

Ultra Violet







X-Rays




Gamma Waves











20









lens





the principal

axis







Diagrams





towards the lens


21




























22













produce an image


in front of F











23



film (at infinity)

gt2F Between F


Image on a film

(close up)


Between 2F and F



ltF ltF (on same


Magnifying glass

Magnification









require a medium






are on the far left


24






vacuum)






Radio Waves



Microwaves




25














Infra Red





our skin



for free

Visible Light








26

Ultra Violet







X-Rays




Gamma Waves











21




























22













produce an image


in front of F











23



film (at infinity)

gt2F Between F


Image on a film

(close up)


Between 2F and F



ltF ltF (on same


Magnifying glass

Magnification









require a medium






are on the far left


24






vacuum)






Radio Waves



Microwaves




25














Infra Red





our skin



for free

Visible Light








26

Ultra Violet







X-Rays




Gamma Waves











22













produce an image


in front of F











23



film (at infinity)

gt2F Between F


Image on a film

(close up)


Between 2F and F



ltF ltF (on same


Magnifying glass

Magnification









require a medium






are on the far left


24






vacuum)






Radio Waves



Microwaves




25














Infra Red





our skin



for free

Visible Light








26

Ultra Violet







X-Rays




Gamma Waves











23



film (at infinity)

gt2F Between F


Image on a film

(close up)


Between 2F and F



ltF ltF (on same


Magnifying glass

Magnification









require a medium






are on the far left


24






vacuum)






Radio Waves



Microwaves




25














Infra Red





our skin



for free

Visible Light








26

Ultra Violet







X-Rays




Gamma Waves











24






vacuum)






Radio Waves



Microwaves




25














Infra Red





our skin



for free

Visible Light








26

Ultra Violet







X-Rays




Gamma Waves











25














Infra Red





our skin



for free

Visible Light








26

Ultra Violet







X-Rays




Gamma Waves











26

Ultra Violet







X-Rays




Gamma Waves










Theme 3 – Nature of Waves · PDF fileFrequency and Periodic Time are related by a simple formula: f = 1 T ... Since the sounds are travelling at about the same ... Unit 1 – Theme

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