(a)[2]
State the meaning of amplitude modulation (AM) of a radio wave.
(b)
An audio signal modulates a radio wave. Figure 5.1 shows how the amplitude of the modulated wave varies with frequency $f$.
(b(i))[1]
Determine the carrier wave’s wavelength.
(b(ii))[1]
Determine the modulated wave’s bandwidth.
(b(iii))[1]
Determine the highest frequency of the audio signal.
(c)[3]
The power of a radio signal at a transmitter is $P_T$. At a receiver, the received power $P_R$ is given by $$P_R = \frac{0.082 P_T}{x^2}$$ where $x$ is the distance, in metres, between the transmitter and the receiver. For this signal transmission, the attenuation is $73\,\text{dB}$. Determine the distance $x$.