**2. Electromagnetic spectrum**

 Electromagnetic waves propagate at different frequencies. The electromagnetic spectrum is the classification of the waves in accordance to their range of frequencies. The classification is necessary since waves which radiate at different frequencies may be generated by different sources and may exhibit different effects on matters. The names given to the bands of frequencies may be broadly classified, in the order of decreasing wavelength and increasing energy and frequency, as follows:


*Introductory Chapter: Electromagnetism DOI: http://dx.doi.org/10.5772/intechopen.85155* 

(v) ultraviolet radiation

(vi) X-rays

(vii) gamma rays

A summary of the spectrum is given in **Figure 2**. It is to be noted that the frequencies at each edge of the band are merely approximations. The boundaries of each band are difficult to be defined since the waves are continuous and the bands may fade into each other.
