Intermediate 1 Physics

1. Intermediate 1 Physics Telecommunication Questions and Answers Beath High School - Int 1 Physics

2. Intermediate 1 Physics Telecommunication Questions 1 to 10 Questions 11 to 20 Questions 21 to 30 Beath High School - Int 1 Physics

3. 1. The telephone, telegraph and radio are all forms of communication systems. Which of these systems does not need a wire link between the transmitter and the receiver? The radio does not need a wire link between the transmitter and receiver. This is because the signal (the message) is carried on invisible radio waves which need no substance to carry them. Beath High School - Int 1 Physics

4. 2. Louise is listening to her radio and enjoying the music played by Atlantic 252. The signal is transmitted from a radio mast at the other end of the country.   (a) Describe the signal which travels from the radio station to the radio receiver. (b) At what speed does the signal travel? (c) What is transferred from the radio mast to the aerial in her radio? The transmitter sends out invisible waves of energy which we call radio waves. Three hundred million metres per second (300 000 000 m/s) energy Beath High School - Int 1 Physics

5. Power supply aerial tuner decoder amplifier speaker 3. Raymond has drawn a block diagram for a radio but can only remember the first unit. (a) Complete the correct block diagram for the radio system. (b) Describe the function of any three units within the radio receiver. Aerial - Detects all radio waves. Tuner - Selects one radio station. Decoder - Separates the sound signal from the radio wave Amplifier - Makes the small electrical signal stronger. Power Supply - Supplies extra energy to the amplifier. Loudspeaker - Changes the electrical signal into sound. Beath High School - Int 1 Physics

6. 4. A radio display shows a combination of letters and numbers as shown. The numbers tell the listener that the transmitter sends out 102.5 million waves in a certain time. How long a time does it take to send out 102.5 million waves? The time taken is one second. (This is because frequency means the number of waves produced every second.) Beath High School - Int 1 Physics

7. 5. Jason is checking the times of the football broadcasts in his newspaper.   The two radio stations broadcast the same programme at the same time. However, the signals are not identical. In what way are the signals different from each other? They are carried on two different radio frequencies. Beath High School - Int 1 Physics

8. 6. June is listening to a rock concert programme on her radio while her sister Alison is watching the same programme on her television.   (a) What type of wave is detected by the radio and the television set?   (b) What is the difference between the two waves? Radio waves. They are different frequencies. Beath High School - Int 1 Physics

9. 7. Each television station has a name which we are all familiar with. BBC 1; BBC 2; STV; Channel 4; Channel 5 As well as the name, how can a particular broadcast station be identified? It can be identified by its frequency. Beath High School - Int 1 Physics

10. aerial 8. A television is an electronic system, which can be represented by a block diagram, as shown below. (a) The diagram is incomplete. Complete the block diagram showing all the parts of a TV in the correct order. tuner sound decoder Vision decoder sound amplifier Vision amplifier speaker Picture tube Beath High School - Int 1 Physics

11. aerial tuner sound decoder Vision decoder sound amplifier Vision amplifier speaker Picture tube - The aerial detects many radio signals and changes them into electrical signals. 8. A television is an electronic system, which can be represented by a block diagram, as shown below. (b) Describe the function of any four parts of the TV system. - The tuner selects the signal you want. (i.e. the channel of your choice) - The decoders separate the sound and vision signals from the carrier wave. - The amplifiers make the electrical signals stronger. - The loudspeaker changes the audio signal into a sound wave, - The picture tube changes the video signal into pictures. Beath High School - Int 1 Physics

12. 9. A television screen is coated with 3 special chemicals which give out different colours of light energy (red, green and blue). A viewer switches on the set and sees a yellow screen. She knows that yellow light is not emitted by the chemicals on the screen of any TV set. Explain why the viewer can see a colour on the screen which is not one of the 3 colours emitted by the chemicals on the screen. The red and green dots are lit up on the TV screen. These two colours of light combine to make yellow. Beath High School - Int 1 Physics

13. 10. High frequency radio signals are sent from the USA to Britain. The signals are received by a ground station in Cornwall. (a) Describe what happens to the signal after it leaves the American ground station. (b) Weather forecasters on television show us detailed pictures of rain clouds over Britain. How is this kind of information gathered? It is transmitted up to a satellite in orbit. There it is amplified and then retransmitted to Cornwall. A satellite in orbit around the earth takes pictures and transmits them back to earth. Beath High School - Int 1 Physics

14. 11. An army unit on military exercise at the Earth's equator have positioned a satellite dish as shown. During their stay they find there is no need to change the position of the dish, which is pointing vertically upward. Communications are good and are never interrupted. (a) Why is there no need to continually alter the position of the satellite dish? (b) What name is given to the type of satellite being used? (c) What is the purpose of the curved reflector behind the aerial? The satellite stays at the same point above the equator. Geostationary To reflect the signals to a focus at the aerial. Beath High School - Int 1 Physics

15. 12. Mirrors are used in many shops and help security guards to observe customers. (a) Describe what happens to light which strikes the mirror. (b) Complete the following diagram, showing the incident light ray and any other ray produced. It reflects off the mirror at the same angle. The angle of reflection is equal to the angle of incidence. reflected light ray normal Beath High School - Int 1 Physics

16. Long, thin strands of flexible glass through which light can travel. 13. Some lamps use a bundle of optical fibres. (a) What are optical fibres? (b) Describe how optical fibres are used in modern communication systems. A signal is changed into variations in brightness of light. These variations are carried from one end of the fibre to the other by total internal reflection. Beath High School - Int 1 Physics

17. 14. Copper wire is used to transmit electrical signals. However, copper is expensive, heavy and produces heat energy. Signals can now be sent through optical fibres and less energy is wasted. (a) Describe the type of signal which is transmitted through an optical fibre. (b) At what speed does this signal travel through the optical fibre? The signal travels through the fibre as variations in the brightness of the light. 200 000 000 metres per second. (light travels a little slower in glass than it does in air.) Beath High School - Int 1 Physics

18. 14. continued, (c) Complete the diagram below to show how the signal reaches the end of the optical fibre. The light repeatedly reflects off the inside walls of the fibre by total internal reflection until it leaves at the far end. Beath High School - Int 1 Physics

19. 15. Dawn is sitting at home using her personal computer. She can use the computer to gain access to information on the Internet. Information is transmitted to Dawn's computer along an optical fibre. What other device in the home might be connected to this optical fibre? The telephone or television. Beath High School - Int 1 Physics

20. 16. A television aerial is used to receive signals from the various TV transmitters. Some other houses in the street receive their television signals via optical fibres. Give one advantage and one disadvantage of the use of optical fibres to transmit signals. Advantage: don’t need aerials/dishes; not affected by bad weather Disadvantage: the street/garden has to be dug up to install it Beath High School - Int 1 Physics

21. 17. A telephone message is transmitted from Glasgow to Edinburgh. (a) What name is given to the part of the system which sends the signal ? (b) What name is given to the part of the system which picks up the signal? The transmitter. (which is the microphone in the mouthpiece) The receiver. (which is the loudspeaker in the earpiece) Beath High School - Int 1 Physics

22. 18. Telephones are of various types and are linked in different ways. The signal can be transmitted between phones using three different types of link. What are the three methods of transmitting a message between the transmitting and receiving telephones? - by wires - by radio signals - by optical fibres Beath High School - Int 1 Physics

23. 19. Mobile phones are being used more and more in the modern world. The mobile phone is a small portable telephone which has no external wiring, unlike conventional phones. (a) What are the two essential parts of a mobile phone, which allows the user to send and receive messages? (b) Using a mobile phone is not always the best way of contacting someone. Give one advantage and one disadvantage of mobile phone use. the mouthpiece (transmitter) the earpiece (receiver) advantage: people can get in touch quickly and easily disadvantage: there is no signal in some areas of the country; it’s use can distract drivers and cause accidents Beath High School - Int 1 Physics

24. inside the mouthpiece 20. While dismantling a telephone in the Physics lab, Alex discovers a microphone inside the handset. (a) Was the microphone found inside the mouthpiece or earpiece? (b) A loudspeaker was also removed from the telephone handset. Which part of the handset contained the loudspeaker? the earpiece Beath High School - Int 1 Physics

25. sound energy to electrical energy 21. Microphones are used in phones, tape recorders and public address systems. State the energy change which takes place in a microphone. Beath High School - Int 1 Physics

26. electrical energy to sound energy 22. Loudspeakers are used in phones, stereo systems, radios and televisions. State the energy change which takes place in a loudspeaker. Beath High School - Int 1 Physics

27. 23. A telephone cable contains bundles of copper wire which carry the signal. What is the approximate speed of the signal which travels along the wire? 300 000 000 metres per second (the speed of light) Beath High School - Int 1 Physics

28. 24. A book publisher has to send a price list to a school. The price list is required urgently. (a) How could the price list be sent to the school very quickly? You should describe the transmitter, receiver and how the two are linked together. (b) Why is this method used so often nowadays? It could be sent by fax. The list is scanned by the sending fax machine. The image is sent as signal along the phone line. Another fax machine prints out a copy at the other end. It is much faster than sending a copy of the list by post. Beath High School - Int 1 Physics

29. 25. A signal generator is used to produce sounds from a loudspeaker. The loudness and the frequency of the note can be changed. The signal is displayed on the screen of an oscilloscope. (a) Describe how the oscilloscope pattern changes when the loudness of the sound increases and the frequency stays the same. The height of the wave on the screen gets bigger, but the number of waves does not change. Beath High School - Int 1 Physics

30. 25. A signal generator is used to produce sounds from a loudspeaker. The loudness and the frequency of the note can be changed. The signal is displayed on the screen of an oscilloscope. (b) Describe how the oscilloscope pattern changes when the frequency increases and the loudness stays the same. The number of waves across the screen changes, but the height of the waves does not change. Beath High School - Int 1 Physics

31. radio 26. Use the information in the given passage to answer the questions below. (a) Complete the following sentences: Satellites receive .......................... signals transmitted from Earth. The satellite then .......................... these .......................... signals back to .......................... (b) Explain the meaning of the term "Geostationary satellite" (c) Why are Geostationary satellites very useful in modern communication systems? radio transmits earth A satellite which stays above the same point on the equator. There is no need to adjust the positions of the ground station satellite dishes. Beath High School - Int 1 Physics

32. 27. The graph below shows how the time it takes a satellite to go round the Earth changes with its height above the Equator. (a) Use the graph to find the height of a Geostationary satellite. (b) A spy satellite has to orbit the Earth twice each day. Use the graph to find the height of this spy satellite. The period is 24 hours which is about 38 000 km A period of 12 hours is at a height of 21 000 km Beath High School - Int 1 Physics

33. 28. The telecommunication system linking two towns uses copper wires. This system is being replaced by one which uses optical fibres. Jamil and Gina want to compare the time taken for signals to travel through these two different types of connector, copper wires and optical fibres. A length of copper wire and a length of optical fibre are each connected to a telephone and a timing device as shown in the diagram. The timing device can measure the time it takes a signal to travel along the copper wire and the optical fibre. (a) Give two reasons why this not a fair test. The wires and fibres are different lengths – this would make a difference They are different thicknesses – this would not make a difference Beath High School - Int 1 Physics

34. 28. (b) Jamil and Gina changed their test to make it fair. The time taken for the signal to travel each of the connectors is given in the table below. (i) Which signals, electrical or light, take the shortest time to travel along the connector? (ii) Explain in which connector, copper wire or optical fibre, the signals take least time to travel. The electrical signals take the shorter time to travel. The signals take less time in the copper wire. This is because the electrical signal travels faster in the wires than the optical signal in the fibre. Beath High School - Int 1 Physics

35. 29. A student finds the following table in a physics book. It contains information on groups of radio waves. Complete the following diagram which shows the radio frequency ranges and their uses. Use the information in the table above to complete your diagram. The use of 300 kHz to 3 MHz has been filled in for you. long range radio communication high quality radio communication TV and mobile phones Beath High School - Int 1 Physics

36. a m p l i f i e r g e o s t a t i o n a r y s e d 30. The following is part of a crossword puzzle that has clues about telecommunications. Complete the part of the crossword shown. The clues are as follows: DOWN: 1. This part of the radio needs a battery to supply it with energy. 2. Twenty four hour per day communication systems often use this type of satellite. ACROSS: 3. Radio signals travel from Glasgow to London in a very short time. This is because radio waves have a very high 4. Mixing red, green and blue light produces this colour. w h i t Beath High School - Int 1 Physics

37. Intermediate 1 Physics Telecommunication End of Questions and Answers Beath High School - Int 1 Physics