History of electromagnetic spectrum discoveryįor most of history, visible light was the only known part of the electromagnetic spectrum. Other technological uses are described under electromagnetic radiation. Spectroscopy is used to study the interactions of electromagnetic waves with matter. 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.
Radiation of visible light wavelengths and lower are called nonionizing radiation as they cannot cause these effects. Exposure to these rays can be a health hazard, causing radiation sickness, DNA damage and cancer. Gamma rays, X-rays, and high ultraviolet are classified as ionizing radiation as their photons have enough energy to ionize atoms, causing chemical reactions. 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. 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. 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 spectrum covers electromagnetic waves with frequencies ranging from below one hertz to above 1025 hertz, corresponding to wavelengths from thousands of kilometers down to a fraction of the size of an atomic nucleus. Watch this cool video made by NASA explaining the whole thing! The electromagnetic spectrum is the range of frequencies (the spectrum) of electromagnetic radiation and their respective wavelengths and photon energies.