<Tr> <Td> </Td> <Td> </Td> <Td> Freq = Frequency </Td> </Tr> <P> The electromagnetic spectrum is the range of frequencies (the spectrum) of electromagnetic radiation and their respective wavelengths and photon energies . </P> <P> The electromagnetic spectrum covers electromagnetic waves with frequencies ranging from below one hertz to above 10 hertz, corresponding to wavelengths from thousands of kilometers down to a fraction of the size of an atomic nucleus . This frequency range is divided into separate bands, and the electromagnetic waves within each frequency band are called by different names; beginning at the low frequency (long wavelength) end of the spectrum these are: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays at the high - frequency (short wavelength) end . The electromagnetic waves in each of these bands have different characteristics, such as how they are produced, how they interact with matter, and their practical applications . The limit for long wavelengths is the size of the universe itself, while it is thought that the short wavelength limit is in the vicinity of the Planck length . Gamma rays, X-rays, and high ultraviolet are classified as ionizing radiation as their photons have enough energy to ionize atoms, causing chemical reactions . Exposure to these rays can be a health hazard, causing radiation sickness, DNA damage and cancer . Radiation of visible light wavelengths and lower are called nonionizing radiation as they cannot cause these effects . </P> <P> In most of the frequency bands above, a technique called spectroscopy can be used to physically separate waves of different frequencies, producing a spectrum showing the constituent frequencies . Spectroscopy is used to study the interactions of electromagnetic waves with matter . Other technological uses are described under electromagnetic radiation . </P>

The wavelength of light in the x-ray region of the electromagnetic spectrum is