Electromagnetic radiation refers to the electromagnetic field waves radiating through space-time, carrying electromagnetic radiant energy.
It includes radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.
Types of Electromagnetic Wave
Electromagnetic waves are classified based on the length of the wavelength. The length of the antenna used in wireless communication is the most efficient when it is half the electromagnetic wave wavelength. The energy of an electromagnetic wave increases as the wavelength gets shorter.
c: speed of light(3×108m／s)
λ: wavelength(m)
υ: frequency(Hz)
Electromagnetic waves go at a speed of 300,000 km per second in a vacuum. Nothing is faster than light in this world.
| Representative Wavelength | Frequency | Photon Energy | |
| Gamma ray | 50 fm | 6 ×1021 Hz | 25 MeV |
| X-ray | 50 pm | 6 ×1018 Hz | 25 keV |
| ultraviolet ray | 100 nm | 3 ×1015 Hz | 12 eV |
| Visible light | 550 nm | 5 ×1014 Hz | 2 eV |
| Infrared ray | 10 μm | 3 ×1013 Hz | 120 meV |
| Microwave | 1 cm | 3 ×1010 Hz | 120 μeV |
| Radio wave | 1 km | 3 ×105 Hz | 1.2 neV |