(a(i))[1]
As infra-red radiation travels through an optic fibre, it is attenuated. State what attenuation means.
(a(ii))[4]
The infra-red radiation is sent as a sequence of pulses. State and explain two advantages of using digital, rather than analogue, transmission of information.
(b)[2]
An optic fibre of length $36\,\text{km}$ has an input light power of $145\,\text{mW}$. Its output light power is $29\,\text{mW}$. Calculate, in $\text{dB km}^{-1}$, the attenuation per unit length of the optic fibre.