(a) The diagram represents part of the electromagnetic spectrum.
(i) Visible light travels through air at 300 000 000 m/s.
Why can we assume that radio waves travel through air at the same speed as light?
(1 mark)
(ii) A radio station broadcasts at a frequency of 200 kHz.
Use the following equation to calculate the wavelength of the waves broadcast by this radio station. Show clearly how you work out your answer.
wave speed = frequency × wavelength
Wavelength = ............................... m
(1 mark)
(iii) Draw a vertical line on the diagram above to show the position of this radio wave in the electromagnetic spectrum.
(1 mark)
(b) Many radio stations now broadcast digital signals instead of analogue signals.
(i) What is an analogue signal?
(1 mark)
(ii) Give one reason why a radio station would broadcast digital signals instead of analogue signals.
(1 marks)
(c) A student thinks that because energy cannot be destroyed it is not possible to waste energy. So he leaves his radio, TV and computer on all the time, even when there is no one in the house.
Explain why he is wrong about not being able to waste energy.
(2 marks)
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From Q5 P1 AQA January 2007