(a)[1]
Suggest why attenuation of a signal in channels of communication is normally measured on a logarithmic scale instead of a linear one.
(b(i))[1]
For a certain channel of communication with low attenuation, the input power is $6.5\,\text{mW}$ and the attenuation per unit length is $1.8\,\text{dB km}^{-1}$. Suggest the name of this channel of communication.
(b(ii))[3]
Calculate the distance for which the signal power falls to $1.5 \times 10^{-15}\,\text{W}$.