Intermediate 1 Physics

Intermediate 1 Physics Telecommunication • Radio • Television • Satellites • Optical Fibres • Telephone Beath High School - Int 1 Physics

Intermediate 1 Physics Telecommunication • Radio Beath High School - Int 1 Physics

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. Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

Radio Parts of a radio receiver The five parts are, a _ _ _ _ _ t _ _ _ _ d _ _ _ _ _ _ a _ _ _ _ _ _ _ _ l _ _ _ _ _ _ _ _ _ aerial tuner decoder amplifier loudspeaker Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

Radio frequency high A h _ _ _ frequency wave looks like this: A l _ _ frequency wave looks like this: low Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

Intermediate 1 Physics Telecommunication • Television Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

Television 300 000 000 high frequency 300 000 000 waves Beath High School - Int 1 Physics

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. Beath High School - Int 1 Physics

Parts of a television receiver Aerial tuner Sound decoder Vision decoder Sound amplifier Vision amplifier loudspeaker Picture tube Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

Television – Colour pictures RED + GREEN = Y _ _ _ _ _ GREEN + BLUE = C _ _ _ _ BLUE + RED = M _ _ _ _ _ _ YELLOW CYAN MAGENTA Beath High School - Int 1 Physics

Intermediate 1 Physics Telecommunication • Satellites Beath High School - Int 1 Physics

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. Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

Curved Reflectors Ray diagram showing how radio waves are brought to a f _ _ _ _ by a c _ _ _ _ _ r _ _ _ _ _ _ _ _ . focus curved reflector. Beath High School - Int 1 Physics

Curved Reflectors Aerial placed at the f _ _ _ _ focus C _ _ _ _ _ reflector receiver Curved Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

Curved Reflectors Very large dish aerials are used to detect radio waves from distant stars. These detectors are called r _ _ _ _ t _ _ _ _ _ _ _ _ _ . radio telescopes. Beath High School - Int 1 Physics

Intermediate 1 Physics Telecommunication • Optical fibres Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

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. Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

Intermediate 1 Physics Telecommunication • Telephone Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

Telephone Part Energy Change microphone Sound to electrical loudspeaker Electrical to sound Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

Energy changes in a telephone system Earpiece An earpiece receives the message. Electrical energy is changed back to s _ _ _ _ in the loudspeaker. sound Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

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. Beath High School - Int 1 Physics

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 Beath High School - Int 1 Physics

Intermediate 1 Physics