Light waves are electromagnetic waves . They do not need a material medium for their propagation . Light waves are transverse waves by nature .They show the phenomena of reflection , refraction , dispersion , diffraction , interferences ,and polarization .
Light waves move fastest in vacuum and their velocity decreases in denser medium .Light waves travel faster in air as compared to solid and liquid .there is no effect of change in temperature or humidity on velocity of light .
Light is radiant energy, usually referring to electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight.
Visible light is usually defined as having a wavelength in the range of 400 nanometres (nm), or 400×10
−9 m, to 700 nanometres – between the infrared, with longer wavelengths and the ultraviolet, with shorter wavelengths.
These numbers do not represent the absolute limits of human vision, but
the approximate range within which most people can see reasonably well
under most circumstances. Various sources define visible light as
narrowly as 420 to 680
to as broadly as 380 to 800 nm.
Under ideal laboratory conditions, people can see infrared up to at least 1050 nm,
children and young adults ultraviolet down to about 310 to 313 nm.
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