ABSTRACT
Special investigations are performed on real live patients, as distinct from laboratory investigations, which are performed on tissues or body fluids obtained from a patient.
There are a large number of signals and wave forms which belong to the electro magnetic spectrum. The wave length is the distance from peak to peak of the wave form and the frequency is the number of waves which pass a point in unit time. The waves travel at the speed of light, which itself is part of the spectrum.
