Credit https://en.wikipedia.org/wiki/Electromagnetic_spectrum
The electromagnetic spectrum is the range of frequencies of electromagnetic radiation and their respective wavelengths and photon energies. Frequencies range from below one hertz to above 1025 hertz, corresponding to wavelengths from thousands of kilometers down to a fraction of an atomic nucleus, with the limit around the Planck length. The higher the frequency, the shorter the wavelength.
Photon energy is the energy carried by a single photon. The photon is a particle (boson) that is the quantum of the electromagnetic spectrum, and the force carrier for the electromagnetic force. Photons are massless, so they always move at the speed of light in vacuum.
The types of electromagnetic radiation are broadly classified into the following classes:
| Class | Frequency | Wavelength | Photon Energy | |
|---|---|---|---|---|
| radio waves | 3 Hz to 300 GHz | 100000 km to 1 mm | 12.4 feV to 1.24 meV | Used to transmit information across distances in radio communication systems such as radio broadcasting, television, mobile phones, communication satellites, wireless networking, Global Positioning Systems (GPS), navigational beacons, radar and remote control. They are emitted and received by antennas which uses AC electric current. MRI scanners use strong magnetic fields and radio waves to generate images of the organs in the body. Earth's atmosphere is mainly transparent to radio waves. |
| microwaves | 3 GHz to 300 GHz | 10 cm to 1 mm | 12.4 μeV to 1.24 meV | Microwaves can penetrate into materials and deposit their energy below the surface. This effect is used to heat food in microwave ovens and in industrial heating. They are also used in radar, satellite communication, and wireless networking technologies such as Wi-Fi. |
| infrared | 300 GHz to 400 THz | 1 mm to 750 nm | 1.24 meV to >1.24 eV | Used for astronomy, photography and videography, remote sensors and thermal and night imaging. Astronomers observe objects in the infrared portion of the electromagnetic spectrum using optical telescopes. |
| light | 400 THz to 790 THz | 380 nm to 760 nm | >1.24 eV | The Sun emits its peak power in the visible region, allowing chemical mechanisms in human and animal vision and plant photosynthesis. A rainbow or light refracted through a prism shows the optical or visible range. Light propagates as waves but when a wave of light is transformed and absorbed as a photon, the wave function collapses. This dual wave-like and particle-like nature of light is known as the wave–particle duality. |
| ultraviolet | 790 THz to 30 PHz | 1 μm to 10 nm | 1.24 eV to 124 eV | This is the start of ionizing radiation where photons are energetic enough to ionize atoms, separating electrons from them, and thus causing chemical reactions which can damage living tissue (for example sunburn or it can lead to cancer). Most of the Sun's damaging UV wavelengths are absorbed by the atmosphere or blocked by the ozone layer before they reach the surface. This leaves less than 3% of sunlight at sea level. UV can cause substances to glow with visible light with an effect called fluorescence. |
| X-rays | 300 PHz to 30 EHz | 10 pm to 100 pm | 1.24 keV to 124 keV | X-rays can pass through many substances with little absorption, and can be used to 'see through' objects, useful in diagnostic X-ray imaging machines in medicine. The accretion disks around neutron stars and black holes emit X-rays, as do stellar coronas. X-ray telescopes must be placed outside the Earth's atmosphere to see these astronomical X-rays, since the atmosphere of Earth is mostly opaque to X-rays. |
| gamma rays | 300 EHz | 1 pm | 1.24 MeV | In astronomy they are valuable for studying high-energy objects or events, also done with telescopes outside the Earth's atmosphere. Used for diagnostic imaging in nuclear medicine, an example being PET scans. Produced by matter-antimatter collisions, and gamma-ray bursts are produced by astronomical events such as quasars. |