(a)[1]
State the meaning of attenuation in a signal.
(b(i))[1]
A transmission cable is $30\,\text{km}$ long. The attenuation per unit length of the cable is $2.4\,\text{dB km}^{-1}$. Calculate the total attenuation, in $\text{dB}$, for a signal sent along the cable.
(b(ii))[3]
Calculate the ratio $\dfrac{\text{input power of signal}}{\text{output power of signal}}$.
(c)[1]
Using your answers in (b), suggest why attenuation of transmitted signals is normally expressed in $\text{dB}$.