Term
| How does the speed of sound compare with the speed of light? Give example. |
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Definition
| Speed of light is about 1,000,000 times more than the speed of sound. |
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Term
| Describe a method of measuring the speed of sound in air which uses the relationship between d, v and t. |
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Definition
| Two microphones attatched to a timer method. |
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Term
| Name one way of transmitting signals. |
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Definition
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Term
| Describe a wave in terms of frequency, wavelength, speed, energy (transfer) and amplitude. |
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Definition
| Frequency is number of waves produced per second. Wavelength is the length from crest to crest. Speed is distance travelled over time. Energy transfer is the amount of energy the wave holds. Amplitude is height from rest to crest. |
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Term
| Explain why f x lamda is the same as d / t for calculating the speed of waves. |
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Definition
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Term
| Describe a method of sending a message using code. |
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Definition
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Term
| Transmitters and receivers are used for what? |
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Definition
| Transmitting and receiving waves. |
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Term
| State the name of a device which allows long range communication using wires between the transmitter and receiver. |
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Definition
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Term
| What are the energy changes in a microphone and a loudspeaker? |
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Definition
| Sound to electrical, and vice versa. |
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Term
| State the devices in a telephone mouthpiece and an earpiece. |
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Definition
| Transmitter and receiver. |
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Term
| What is transmitted along the communicating wires during a telephone communication? |
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Definition
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Term
| Explain the pattern of an electrical signal in a telephone wire in terms of loudness and frequency. |
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Definition
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Term
| What's the speed of sound in air, and a signal along a telephone cable? |
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Definition
Sound in air - 340 m/s
Telephone signal - 3 x 10 to the 8 m/s |
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Term
| What will the change in the wave be when it gets louder, and the frequency gets higher? |
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Definition
| Higher amplitude and higher pitch (waves more squashed together) |
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Term
| How do frequency and amplitude relate to sound? |
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Definition
| High frequency = high pitch, high amplitude = loud volume |
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Term
| WTF is an optical fibre?! |
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Definition
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Term
| What are optical fibres used for in telecommunications? |
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Definition
| Long distance phone calls, broadband etc. |
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Term
| What are the two main types of cables used to transmit information in telecommunication? |
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Definition
| Copper and Optical fibres. WOOT! |
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Term
| Why are optical fibres better than copper cables? |
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Definition
| Cheaper, less repeater used, carry more information, less information is lost. |
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Term
| Light can be reflected. WTF is that supposed to mean? |
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Definition
| It gets bounced, ya noob. |
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Term
| What is the law of reflection? |
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Definition
| angle of reflection = angle of incidence. |
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Term
| What is the speed of a signal along an optical fibre? |
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Definition
| 2 x 10 to the 8 m/s (this means copper cables are actually faster! but still crap.) |
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Term
| What are the six main parts of a radio receiver?? (also, what do they do?) |
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Definition
| ariel (gets the radio signals), tuner (selects one signal), decoder (removes carrier wave), amplifier (increases amplitude of wave), battery (powers amplifier), loudspeaker (turns signal into audio signal so you can hear it!) |
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Term
| Whats the general principle of radio transmission in terms of transmitter, carrier wave, amplitude modulation and receiver? |
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Definition
| Well..... change amplitude of carrier wave. |
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Term
| What are the 7 main parts of a television receiver? (yeah, just learn it.... even tho it sucks) |
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Definition
| ariel (picks up signals), tuner (selects one signal), audio decoder (demodulates audio), video decoder (demodulates video), audio/video amplifiers (increases amplitude of audio/video signal), loudspeaker (turns audio signal into sound so we can hear it), tv tube (turn electrical signal into light so we can see it) |
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Term
| What is the general principle of television transmission in terms of transmitter, carrier wave, modulation, video and audio receivers? |
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Definition
| Combine the audio and video signals and modulate the signal. |
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Term
| How is a picture produced on a tv in terms of line build-up? |
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Definition
| The electron gun scans across the 625 lines that make up a tv screen so quickly it appears like a picture. |
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Term
| How is a moving picture produced on a black and white tv? |
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Definition
| The electron gun scans across the tv screen and changes the brightness by altering the amount of electrons fired. The images are made so quickly that our eye cant keep up and sees it as a moving picture. |
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Term
| What are the three colours used in a colour tv? |
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Definition
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Term
| If you mix the three colours used on a colour tv, what do you get? |
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Definition
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Term
| Give three examples of long range communication which do not need cables between transmitter and receiver? |
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Definition
| Mobile phones, tv and radio. |
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Term
| What carries energy between the transmitter and receiver in microwave, radio and tv telecommunication systems? |
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Definition
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Term
| What is the speed of microwave, radio and tv signals through air? |
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Definition
| 3 x 10 to the 8 m/s (aka the speed of light) |
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Term
| What properties of the transmitted radio waves allow us to identify the source transmitter? |
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Definition
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Term
| What are the differences in properties of radio bands? |
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Definition
| LW has good diffraction and travels far, MW is for both local and distant broadcasts, SW is for navigation and barely diffracts. |
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Term
| How does wavelength affect tv and radio reception in terms of diffraction? |
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Definition
| If a wave hits an obstacle and has to diffract, LW is going to diffract more than MW and thus is more likely to be recepted. This is also why it is easier to receive radio signals than tv signals. |
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Term
| Why are curved reflectors used? |
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Definition
| Because it is easy to focus all the signals on to one point. |
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Term
| Where are curved reflectors used in telecommunications? |
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Definition
| Well, thats what a satellite dish is, simpleton. |
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Term
| How does the height of a satellite affect the time it takes to orbit the earth? |
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Definition
| The higher a satellite is, the longer it takes to orbit the earth. (like the difference between running round a track in the outside lane instead on the inside lane) |
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Term
| What is geostationary orbit? |
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Definition
| Its when a satellite goes round the earth so that it stays above the same point all the time. |
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Term
| How does a tv signal get broadcast to another country? |
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Definition
| It is sent to a satellite which receives it and then transmits it down to the other country. |
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