One of the topics studied in GCSE Science is mechanical and electromagnetic waves. This is one of six quizzes on that particular subject and it looks specifically at using transverse electromagnetic waves for communication.
We know that there are two types of wave - transverse waves and longitudinal waves. Radio waves, microwaves, infrared, visible light, ultraviolet light, X-rays and gamma rays are all transverse waves. They are also all members of the electromagnetic spectrum and some of them can be used for communication. For the exam you should know some typical examples of how and where they are used, and any associated hazards.
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One difficulty with using these electromagnetic waves for communication is that they travel in straight lines. This can cause problems because the surface of the Earth is curved. For the longer waves, like radio, this is not a massive issue because these waves can be reflected and they also diffract. Diffraction is the spreading out of a wave when it passes through a gap or around an object. The gap or object needs to be about the same size or smaller than the wavelength for diffraction to occur.
Radio waves can travel long distances because they can be reflected round the curvature of the Earth. They reflect off the ionosphere (a layer of the Earth's atmosphere) and off the surface of the Earth itself. Each time a wave is reflected it loses a little energy. This means that radio signals get weaker the further you are from the transmitter. It is for that reason that repeater stations are built which boost the signal strength and quality.
Radio waves can also travel round corners because of diffraction and can reach people in the bottom of valleys. It works because hills are comparable in size to the wavelength of radio waves. Diffraction allows radio signals to reach people who are not in direct line with the transmitter. The deeper and narrower the valley, the more difficult it is for them to receive a radio signal that is not coming from directly above.
As any owner of a mobile telephone will know, there are places where you can't get a signal. This is because they work using microwave technology. Microwaves have a much shorter wavelength than radio waves and so don't diffract as easily. They are also blocked more easily than radio waves which is why sometimes you need to move around a building or go outside to find the best signal.
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1.
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Which of the following members of the electromagnetic spectrum has the longest wavelength? |
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[ ] |
Visible light |
[ ] |
Infrared radiation |
[ ] |
Microwaves |
[ ] |
Radio waves |
|
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2.
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Which of the following members of the electromagnetic spectrum has the highest frequency? |
|
[ ] |
Gamma radiation |
[ ] |
X-rays |
[ ] |
Infrared radiation |
[ ] |
Microwaves |
|
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3.
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Which of the following is used in remote control devices for TV's, radios and similar appliances? |
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[ ] |
Gamma radiation |
[ ] |
X-rays |
[ ] |
Infrared radiation |
[ ] |
Microwaves |
|
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4.
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Which of the following is not a disadvantage of wireless communication? |
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[ ] |
The signals can be blocked by thick walls |
[ ] |
Wireless devices must be in range of the transmitter |
[ ] |
Wireless devices can be made to be portable |
[ ] |
Atmospheric conditions can cause a loss of signal |
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5.
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Which type of electromagnetic radiation can be reflected by the ionosphere, a layer of charged particles in the Earth's atmosphere? |
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[ ] |
Visible light |
[ ] |
Infrared radiation |
[ ] |
Microwaves |
[ ] |
Radio waves |
|
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6.
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Which type of electromagnetic radiation travels the slowest? |
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[ ] |
They all travel at the same speed |
[ ] |
Infrared radiation |
[ ] |
Microwaves |
[ ] |
Radio waves |
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7.
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Which of the following is not a way that infrared radiation is used to transmit or receive information? |
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[ ] |
DVD remote control |
[ ] |
Radiant heater |
[ ] |
Optical fibre broadband Internet |
[ ] |
Security lights |
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8.
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Why are microwaves used for communicating with satellites? |
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[ ] |
Microwaves are not refracted by the Earth's atmosphere |
[ ] |
Microwaves are refracted by the Earth's atmosphere |
[ ] |
Microwaves are the only waves that can travel through space |
[ ] |
Other types of wave are not powerful enough to reach that far |
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9.
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Why do mobile telephone users need to be in line of sight with a transmitter to get a signal? |
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[ ] |
Radio waves cannot be diffracted |
[ ] |
Microwaves have too short a wavelength to be diffracted |
[ ] |
Infrared radiation is absorbed by trees, buildings and people |
[ ] |
Microwaves are easily bent upwards into space |
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10.
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Why do some people object to mobile telephone masts being erected near their homes? |
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[ ] |
They interfere with TV signals |
[ ] |
They make a loud humming noise |
[ ] |
They believe that the microwaves are harmful to health |
[ ] |
They attract a lot of birds which leave their droppings on their houses and cars |
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1.
|
Which of the following members of the electromagnetic spectrum has the longest wavelength? |
|
[ ] |
Visible light |
[ ] |
Infrared radiation |
[ ] |
Microwaves |
[x] |
Radio waves |
|
|
2.
|
Which of the following members of the electromagnetic spectrum has the highest frequency? |
|
[x] |
Gamma radiation |
[ ] |
X-rays |
[ ] |
Infrared radiation |
[ ] |
Microwaves |
|
|
3.
|
Which of the following is used in remote control devices for TV's, radios and similar appliances? |
|
[ ] |
Gamma radiation |
[ ] |
X-rays |
[x] |
Infrared radiation |
[ ] |
Microwaves |
|
|
4.
|
Which of the following is not a disadvantage of wireless communication? |
|
[ ] |
The signals can be blocked by thick walls |
[ ] |
Wireless devices must be in range of the transmitter |
[x] |
Wireless devices can be made to be portable |
[ ] |
Atmospheric conditions can cause a loss of signal |
|
|
5.
|
Which type of electromagnetic radiation can be reflected by the ionosphere, a layer of charged particles in the Earth's atmosphere? |
|
[ ] |
Visible light |
[ ] |
Infrared radiation |
[ ] |
Microwaves |
[x] |
Radio waves |
|
|
6.
|
Which type of electromagnetic radiation travels the slowest? |
|
[x] |
They all travel at the same speed |
[ ] |
Infrared radiation |
[ ] |
Microwaves |
[ ] |
Radio waves |
|
|
7.
|
Which of the following is not a way that infrared radiation is used to transmit or receive information? |
|
[ ] |
DVD remote control |
[x] |
Radiant heater |
[ ] |
Optical fibre broadband Internet |
[ ] |
Security lights |
|
|
8.
|
Why are microwaves used for communicating with satellites? |
|
[x] |
Microwaves are not refracted by the Earth's atmosphere |
[ ] |
Microwaves are refracted by the Earth's atmosphere |
[ ] |
Microwaves are the only waves that can travel through space |
[ ] |
Other types of wave are not powerful enough to reach that far |
|
|
9.
|
Why do mobile telephone users need to be in line of sight with a transmitter to get a signal? |
|
[ ] |
Radio waves cannot be diffracted |
[x] |
Microwaves have too short a wavelength to be diffracted |
[ ] |
Infrared radiation is absorbed by trees, buildings and people |
[ ] |
Microwaves are easily bent upwards into space |
|
|
10.
|
Why do some people object to mobile telephone masts being erected near their homes? |
|
[ ] |
They interfere with TV signals |
[ ] |
They make a loud humming noise |
[x] |
They believe that the microwaves are harmful to health |
[ ] |
They attract a lot of birds which leave their droppings on their houses and cars |
|
|