What Is Light

∟What Is Light

This section provides a quick introduction of light, which is a form of energy traveling in the space.

What Is Light? Light is a form of energy traveling in the space.

Light Transfers Energy from Sun to Earth

Structurally, light is made of discrete packets of electromagnetic wave call photons, represented by the symbol γ (gamma). So light is also referred as a form of electromagnetic radiation.

Main properties of photon are:

Photon has a wavelength, λ (lambda), defined as the distance between two peaks of its electric field wave.
Photon has a frequency, ν (nu), defined as the number of peaks of its electric field wave passing a fixed location in a second.
Photon travels at a constant speed of c = 299,792,458 m/s.
Photon's wavelength is inversely proportional to its frequency: λ = c/ν, or c = νλ
Photon's energy, E, is directly proportional to its frequency: E = hν, where h (6.62607015 × 10^-34 J/Hz) is the Planck constant.
Photon's amplitude, A, is related to its frequency as A² = h/ν, or E = (Aν)².
The oscillation direction (polarization direction) of photon's electric field wave is fixed at a 90 degree angle to the traveling direction.
The oscillation direction of photon's magnetic field wave is fixed at a 90 degree angle to the traveling direction and the oscillation direction of the electric field wave.
The electric field wave and the magnetic field wave have the same frequency and travel in phase.
Photon is mass-less.