Revise GCSE Physics


Question:What are the advantages and disadvantages of using light, infrared, microwaves, radio and electrical signals for communication?

Type of signal Advantages Disdvantages
Light Can be seen. Our eye can be the receiver. Damaging to eyes if too bright. Readily scattered by cloud, mist etc. Reqires line of sight. Cannot travel very long distances in fibers.
Infrared Allows much longer distance fiber optic links because glass absorbs much less IR than visible light per mile of fiber. Is invisible and eye safe. Strictly short range when through the air, and requires line of sight.
Radio Diffracts into shadow of large objects. Can follow the curvature of the earth by reflection from ionosphere. Cannot carry as much information due to very long wavelengths compared to other EM radiations.
Electrical Relatively cheap and easy. Uses simpler technology than the others. Requires a wired connection between sender and receiver
Microwaves Can travel through clouds, fog and the various layers of the atmosphere without being completely lost. Requires line of sight between receiver and transmitter.