State what is meant by the amplitude modulation (AM) of a radio wave.

1. (a)State what is meant by the amplitude modulation (AM) of a radio wave.[2]
2. (b)A radio wave is modulated by an audio signal. The variation with frequency f of the amplitude of the modulated wave is shown in [Figure 5.1]. Determine:
3. (b)(i)the wavelength of the carrier wave wavelength = .............................................................. m [1][1]
4. (b)(ii)the bandwidth of the modulated wave bandwidth = ........................................................... kHz [1][1]
5. (b)(iii)the maximum frequency of the audio signal. maximum frequency = ........................................................ kHz [1][1]
6. (c)The power of a radio signal at a transmitter is PT. At a receiver, the received power PR is given by the expression PR = (0.082 PT) / x² where x is the distance, in metres, between the transmitter and the receiver. For the transmission of this signal, the attenuation is 73 dB. Determine the distance x. x = ............................................................... m [3][3]

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