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Intermediate 1 Physics . Telecommunication. Radio. Television. Satellites. Optical Fibres. Telephone. Intermediate 1 Physics . Telecommunication. Radio. Radio. At one time a radio was called a "wireless" because the signal it received did not come through w _ _ _ _ .

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Intermediate 1 physics

Intermediate 1 Physics

Telecommunication

  • Radio

  • Television

  • Satellites

  • Optical Fibres

  • Telephone

Beath High School - Int 1 Physics


Intermediate 1 physics1

Intermediate 1 Physics

Telecommunication

  • Radio

Beath High School - Int 1 Physics


Radio
Radio

At one time a radio was called a "wireless" because the signal it received did not come through w _ _ _ _ .

A radio transmitter s _ _ _ _ out invisible waves of energy which can be picked up by an aerial r _ _ _ _ _ _ _ .

wires.

sends

receiver.

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Radio1
Radio

  • The radio waves can travel through air the air at a speed of 300 000 000 metres per s _ _ _ _ _ . (300 000 000 = 300 hundred million.) This means that they travel l _ _ _ _ distances in a very short time.

second.

large

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Parts of a radio receiver

Radio

Parts of a radio receiver

  • A radio is an electronic system which is used to detect radio w _ _ _ _ and change them into speech and music.

  • Every radio has five main parts, all having a different j _ _ to do.

waves

job

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Parts of a radio receiver1

Radio

Parts of a radio receiver

The five parts are,

a _ _ _ _ _

t _ _ _ _

d _ _ _ _ _ _

a _ _ _ _ _ _ _ _

l _ _ _ _ _ _ _ _ _

aerial

tuner

decoder

amplifier

loudspeaker

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Functions of the main parts of a radio
Functions of the main parts of a radio

radio

Aerial - Detects all r _ _ _ _ waves.

Tuner - Selects one radio s _ _ _ _ _ _ by picking

out one frequency.

Decoder - Separates the s _ _ _ _ signal from the

radio w _ _ _.

Amplifier - Makes the small electrical s _ _ _ _ _

stronger. (The extra e _ _ _ _ _ is supplied

to the amplifier by a battery or the mains).

Loudspeaker - Changes the e _ _ _ _ _ _ _ _ _ signal into

a sound wave.

station

sound

wave.

signal

energy

electrical

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Radio frequency
Radio frequency

different

Each radio station broadcasts on a

d _ _ _ _ _ _ _ _ radio frequency.

The f _ _ _ _ _ _ _ _ of a wave is the number of waves produced in one second.

The frequency is measured in h _ _ _ _ (Hz).

frequency

hertz

1 000 Hz = 1 _ _ _ _ hertz (kHz)

This means 1 000 waves in one second.

1 000 000 Hz = 1 _ _ _ _ hertz (MHz)

This means 1 000 000 waves in one second.

kilo

mega

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Radio frequency1
Radio frequency

high

A h _ _ _ frequency wave looks like this:

A l _ _ frequency wave looks like this:

low

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Radio frequency2
Radio frequency

tune

You can t _ _ _ a radio by selecting the frequency you want.

Forth 1 has a frequency of _ _ . _ MHz ( 97 300 000 Hz) and is a local FM radio station.

97.3

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Radio frequency3
Radio frequency

lower

The medium wave band (MW) contains l _ _ _ _ frequency radio stations like Radio 5, which has a frequency of 909 kHz ( _ _ _ _ _ _ Hz).

909 000

Signs at the side of motorways give d _ _ _ _ _ _ information about radio frequencies.

drivers

FM stations have a

h _ _ _ _ _ frequency than

medium wave (MW)

higher

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Intermediate 1 physics2

Intermediate 1 Physics

Telecommunication

  • Television

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Television
Television

high

A television receiver picks up very h _ _ _ frequency radio waves.

These signals travel at 300 million m _ _ _ _ _ per second through the air but have a higher frequency than signals from a r _ _ _ _ transmitter.

This means radio and T.V. signals travel

at the s _ _ _ speed

metres

radio

same

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Television1
Television

300 000 000

high frequency

300 000 000

waves

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Television2
Television

Each television station transmits a

d _ _ _ _ _ _ _ _ frequency.

different

The following table shows some of the well known television stations and frequencies they use in one area of Scotland.

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Parts of a television receiver
Parts of a television receiver

Aerial

tuner

Sound

decoder

Vision

decoder

Sound

amplifier

Vision

amplifier

loudspeaker

Picture

tube

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Parts of a television receiver1
Parts of a television receiver

radio

Aerial

electrical

- The aerial detects many r _ _ _ _ signals and changes them into e _ _ _ _ _ _ _ _ signals.

- The t _ _ _ _ selects the signal you want.

(i.e. the ch _ _ _ _ _ of your choice)

- The decoders separate the sound and vision signals from the c _ _ _ _ _ _ wave.

tuner

tuner

channel

Sound

decoder

Vision

decoder

carrier

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Parts of a television receiver2
Parts of a television receiver

signals

Sound

amplifier

Vision

amplifier

- The amplifiers make the electrical

s _ _ _ _ _ _ stronger. One amplifier is for the s _ _ _ _ signal and the other amplifier is for the p _ _ _ _ _ _ signal.

- The l _ _ _ _ _ _ _ _ _ _ changes the audio signal into a sound wave,

- The p _ _ _ _ _ _ t _ _ _ changes the video signal into pictures.

sound

picture

loudspeaker

loudspeaker

Picture

tube

picture tube

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Television colour pictures
Television – Colour pictures

three

In a colour television only t _ _ _ _ colours can be produced on the screen.

The three colours are R _ _ , G _ _ _ _ and B _ _ _ .

All the other colours are produced by

m _ _ _ _ _ these three colours.When RED, GREEN and BLUE are all mixed together W _ _ _ _ is produced.

Red,

Green

Blue.

mixing

WHITE

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Television colour pictures1
Television – Colour pictures

light

Any colour can be made by mixing the l _ _ _ _ of

these colours.

You can remember the order of colours in the "star" by

remembering the following:

Rich Young Girls Can Buy Meals

R _ _ Y _ _ _ _ _ G _ _ _ _ C _ _ _ B _ _ _ M _ _ _ _ _ _

Red

Yellow

Green

Cyan

Blue

Magenta

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Television colour pictures2
Television – Colour pictures

RED + GREEN = Y _ _ _ _ _

GREEN + BLUE = C _ _ _ _

BLUE + RED = M _ _ _ _ _ _

YELLOW

CYAN

MAGENTA

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Intermediate 1 physics3

Intermediate 1 Physics

Telecommunication

  • Satellites

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Satellites
Satellites

Radio waves can be sent around the

w _ _ _ _ via satellites.

For example, the American Superbowl competition can be seen l _ _ _ in the U.K. because of the signal being passed on by s _ _ _ _ _ _ _ _.

world

live

satellite.

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Uses of satellites
Uses of satellites

Modern satellites can beam various signals back to the

ground. For example:

T.V. p _ _ _ _ _ _ _ _ _

p _ _ _ _ calls

w _ _ _ _ _ _ pictures

t _ _ _ _ _ _ _ stolen cars.

The satellites o _ _ _ _ the earth and

t _ _ _ _ _ _ _ signals to or

r _ _ _ _ _ _ signals from ground

stations.

programmes

phone

weather

tracking

orbit

transmit

receive

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Geostationary satellites
Geostationary satellites

A Geostationary satellite always remains above the s _ _ _

point of the Equator on the Earth's surface.

The dish on the ground can be set to receive a strong signal and not be m _ _ _ _ again.

same

moved

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Geostationary satellites1
Geostationary satellites

Geostationary Satellites Orbits once every _ _ hours

Orbits above the E _ _ _ _ _ _ .

24

Equator.

Other Satellites Several orbits completed every

24 hours. Height is l _ _ _ than

that of Geostationary

satellites.

less

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Curved reflectors
Curved Reflectors

The signals from satellites travel great distances and a bare aerial cannot pick up a

s _ _ _ _ _ e _ _ _ _ _ signal.

A curved reflector can bring radio waves to a f _ _ _ _ just like curved mirrors cause l _ _ _ _ rays to meet at the focus.

strong enough

focus

light

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Curved reflectors1
Curved Reflectors

Ray diagram showing how radio waves are brought to a f _ _ _ _ by a

c _ _ _ _ _ r _ _ _ _ _ _ _ _ .

focus

curved reflector.

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Curved reflectors2
Curved Reflectors

Aerial placed

at the f _ _ _ _

focus

C _ _ _ _ _

reflector receiver

Curved

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Curved reflectors3
Curved Reflectors

A strong/weak radio signal can be detected if the aerial is positioned at the focus of the curved reflector.

More/Less of the wave energy is collected when these aerials are used.

(This is because the dish collects more/less of the energy in the wave than a bare aerial.

Also its curved shape f _ _ _ _ _ _ the collected energy on to the aerial.)

focuses

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Curved reflectors4
Curved Reflectors

Very large dish aerials are used to detect radio waves from distant stars.

These detectors are called r _ _ _ _ t _ _ _ _ _ _ _ _ _ .

radio

telescopes.

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Intermediate 1 physics4

Intermediate 1 Physics

Telecommunication

  • Optical fibres

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Reflection
Reflection

We can look at our

r _ _ _ _ _ _ _ _ _

in a mirror or the light from any

shiny object being reflected.

The angles i and r are the s _ _ _ size.

reflection

r

the angle of reflection

same

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Optical fibres
Optical fibres

wires.

At one time signals always were sent throughcopperw _ _ _ _ . An e _ _ _ _ _ _ _ _ _ current flows through the phone lines but e _ _ _ _ _ is lost and the signal needs to be boosted every so often at repeater stations. An optical fibre is a very t _ _ _ piece of flexible g _ _ _ _ which can carry l _ _ _ _ energy. The light is

r _ _ _ _ _ _ _ _ between the sides of

the optical fibre.

electrical

energy

glass

thin

light

reflected

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Optical fibres1
Optical fibres

In air, light travels at the s _ _ _ speed as radio waves,

_ _ _ million metres per second.

In optical fibres, the light travels slightly s _ _ _ _ _ at

200 million metres per second.

same

300

slower

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Uses of optical fibres
Uses of optical fibres

More and more people are receiving signals into their homes

which have come through optical f _ _ _ _ _ ,

for example:

cable t _ _ _ _ _ _ _ _ _

p _ _ _ _ calls

h _ _ _ banking

I _ _ _ _ _ _ _ access

fibres,

television

phone

home

Internet

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Uses of optical fibres1
Uses of optical fibres

One disadvantage of using optical fibres is the inconvenience of having to lay the cables u _ _ _ _ _ _ _ _ _ _ which means digging trenches along the pavements.

One advantage is not having to install a satellite d _ _ _ on the wall of the house. Another advantage is that the reception is not affected by b _ _ weather conditions, e.g. heavy s _ _ _ .

underground

dish

bad

snow.

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Optical fibres2
Optical fibres

Copper Cable

Optical Fibre

Comparison of Copper cable and Optical Fibre:

Repeater stations every 4 km

Repeater stations every 1 _ _ km

100

1 000 conversations at a time

11 000 conversations at a time

1 000

11 000

Thick and heavy

T _ _ _ and very l _ _ _ _

Thin

light

Almost 300 million metres per second

_ _ _ million metres per second

200

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Intermediate 1 physics5

Intermediate 1 Physics

Telecommunication

  • Telephone

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Telephone

Mouthpiece

Earpiece

Sound

Sound

Link:copper wire

m………….

l..………….

Carrier: electrical signal

T…………..

R………….

Telephone

long

People can speak to each other, over l _ _ _ distances, by telephone.

Speech is changed into an e _ _ _ _ _ _ _ _ _ signal and changed back into s _ _ _ _ again at the receiver.

electrical

sound

microphone

loudspeaker

Transmitter

Receiver

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Telephone1
Telephone

Part

Energy Change

microphone

Sound to electrical

loudspeaker

Electrical to sound

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Telephone2

M………….

E………….

Sound

Sound

Link: o……. f…….

microphone

loudspeaker

Carrier: l……. signal

Transmitter

Receiver

Telephone

wire

Phones can be connected by copper w _ _ _ or optical f _ _ _ _ (shown below).

fibre

Mouthpiece

Earpiece

Link: optical fibre

Carrier: light signal

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Mobile phones

Mouthpiece

Earpiece

Sound

Sound

Link: no physical link

microphone

loudspeaker

Carrier: r……. w…..

Transmitter

Receiver

Mobile phones

radio

Mobile phones rely on r _ _ _ _ signals travelling from the transmitter to the

r _ _ _ _ _ _ _ . These signals carry

receiver.

the message through air without wires.

Carrier: radio wave

A mobile phone has to be a combined radio

t _ _ _ _ _ _ _ _ _ _ and receiver.

transmitter

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Mobile phones1
Mobile phones

There are advantages and disadvantages to using a mobile phone.

You do not have to find a phone box when you want to make an urgent call. However, some drivers cause a _ _ _ _ _ _ _ _ when they use a m _ _ _ _ _ phone and drive at the same time.

accidents

mobile

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Mobile phones2
Mobile phones

Some locations prevent you using the mobile phone, for example:

• in the Scottish H _ _ _ _ _ _ _ _ (the hills s _ _ _ the signal)

• inside l _ _ _ tunnels.

Highlands

stop

long

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Energy changes in a telephone system
Energy changes in a telephone system

Mouthpiece

A mouthpiece transmits the message. S _ _ _ _ energy enters the m _ _ _ _ _ _ _ _ _ and is changed into electrical e _ _ _ _ _ .

Sound

mouthpiece

energy

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Energy changes in a telephone system1
Energy changes in a telephone system

Earpiece

An earpiece receives the message.

Electrical energy is changed back to s _ _ _ _ in the loudspeaker.

sound

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Energy changes in a telephone system2
Energy changes in a telephone system

Telephone signals

Copper wires carry the message in the form of an

e _ _ _ _ _ _ _ c _ _ _ _ _ _ ,

which travels at almost _ _ _ million metres per second.

electric current

300

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facsimile.

copy

Fax

Fax is the shortened term for f _ _ _ _ _ _ _ _ .

A document is inserted into the machine and a c _ _ _

of the document is received at the other end of the p _ _ _ _ line.

Important documents can be transferred very q _ _ _ _ _ _. Before this invention, documents had to go by p _ _ _ .

phone

quickly.

post.

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Oscilloscope patterns
Oscilloscope patterns

The signal in a phone line can be displayed on the screen of an oscilloscope. The v _ _ _ _ _ _ of the signal varies as the caller speaks into the mouthpiece.

voltage

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Oscilloscope patterns1
Oscilloscope patterns

higher

Loudness

Loud sounds produce a h _ _ _ _ _ voltage signal than a quiet soft sound. The a _ _ _ _ _ _ _ _ is greater for high voltages.

amplitude

smaller

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Oscilloscope patterns2
Oscilloscope patterns

Frequency

Some sounds have a higher pitch (frequency) than others.

For example, sound ‘A’ below could be a horn which produces a l _ _ pitched sound. Sound ‘B’ below could be a whistle which produces a high p _ _ _ _ _ _ s _ _ _ _ .

low

pitched sound.

high

frequency

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Oscilloscope patterns3
Oscilloscope patterns

The oscilloscope can display waves of different frequencies.

A high frequency wave produces m _ _ _ waves per second than low a frequency wave.

more

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Intermediate 1 physics6

Intermediate 1 Physics

Telecommunication

End of Unit

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