nl = c (1)

All electromagnetic waves travel at the same velocity but vary in wavelength (l) and frequency (n) according to the relationship,

nl = c (1)

An electromagnetic wave form is depicted in figure 8. The wave form is considered to be traveling from left to right and the sinusoidal wave form in the vertical axis represents the electrical vector and the wave form in the horizontal axis represents the magnetic vector.

Figure 8. An Electromagnetic Wave form

In general, it is the electric vector that interacts with physical matter but, although there may be some interactions with the magnetic vector, they are considered to be minimal compared with those from the electric field. The propagation of electromagnetic waves occurs in quanta where the energy associated with each quanta (E) is given by,