Electromagnetic spectrum

The electromagnetic spectrum is the range of frequencies (the spectrum) of electromagnetic radiation and their respective wavelengths and photon energies.

Class				Wave- length ${\displaystyle \lambda }$	Freq- uency ${\displaystyle f}$	Energy per photon ${\displaystyle E}$
Ionizing radiation	γ	Gamma rays		1 pm	300 EHz	1.24 MeV
				10 pm	30 EHz	124 keV
	HX	Hard X-rays
				100 pm	3 EHz	12.4 keV
	SX	Soft X-rays
				1 nm	300 PHz	1.24 keV
				10 nm	30 PHz	124 eV
	EUV	Extreme ultraviolet
				100 nm	3 PHz	12.4 eV
	NUV	Near ultraviolet, visible
				1 μm	300 THz	1.24 eV
	NIR	Near infrared
				10 μm	30 THz	124 meV
	MIR	Mid infrared
				100 μm	3 THz	12.4 meV
	FIR	Far infrared
				1 mm	300 GHz	1.24 meV
Micro- waves	EHF	Extremely high frequency
				1 cm	30 GHz	124 μeV
	SHF	Super high frequency
				1 dm	3 GHz	12.4 μeV
	UHF	Ultra high frequency
				1 m	300 MHz	1.24 μeV
Radio waves	VHF	Very high frequency
				10 m	30 MHz	124 neV
	HF	High frequency
				100 m	3 MHz	12.4 neV
	MF	Medium frequency
				1 km	300 kHz	1.24 neV
	LF	Low frequency
				10 km	30 kHz	124 peV
	VLF	Very low frequency
				100 km	3 kHz	12.4 peV
	ULF	Ultra low frequency
				1 Mm	300 Hz	1.24 peV
	SLF	Super low frequency
				10 Mm	30 Hz	124 feV
	ELF	Extremely low frequency
				100 Mm	3 Hz	12.4 feV
Sources: File:Light spectrum.svg[1][2][3]

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. 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. There is no known limit for long and short wavelengths. Extreme ultraviolet, soft X-rays, hard X-rays and gamma rays are classified as ionizing radiation because their photons have enough energy to ionize atoms, causing chemical reactions. Radiation of visible light and longer wavelengths are classified as nonionizing radiation because they have insufficient energy to cause these effects.

Throughout most of the electromagnetic spectrum, spectroscopy can be used to separate waves of different frequencies, producing a spectrum of the constituent frequencies. Spectroscopy is used to study the interactions of electromagnetic waves with matter.[4]