light
Light is everywhere in our world. We need it to see: it carries information from the world to our eyes and brains. Seeing colors and shapes is second nature to us, yet light is a perplexing phenomenon when we study it more closely.
Here are some things to think about:
Our brains and eyes act together to make extraordinary things happen in perception. Movies are sequences of still pictures. Magazine pictures are arrays of dots.
Light acts like particles—little light bullets—that stream from the source. This explains how shadows work.
Light also acts like waves—ripples in space—instead of bullets. This explains how rainbows work. In fact, light is both. This "wave-particle duality" is one of the most confusing—and wonderful—principles of physics.
Light is radiant energy, usually referring to electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight.[1] 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.[2][3] 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[4][5] to as broadly as 380 to 800 nm.[6][7] Under ideal laboratory conditions, people can see infrared up to at least 1050 nm,[8] children and young adults ultraviolet down to about 310 to 313 nm.[9][10][11]
Primary properties of visible light are intensity, propagation direction, frequency or wavelength spectrum, and polarisation, while its speed in a vacuum, 299,792,458 meters per second, is one of the fundamental constants of nature. Visible light, as with all types of electromagnetic radiation (EMR), is experimentally found to always move at this speed in vacuum.[citation needed]
In common with all types of
Here are some things to think about:
Our brains and eyes act together to make extraordinary things happen in perception. Movies are sequences of still pictures. Magazine pictures are arrays of dots.
Light acts like particles—little light bullets—that stream from the source. This explains how shadows work.
Light also acts like waves—ripples in space—instead of bullets. This explains how rainbows work. In fact, light is both. This "wave-particle duality" is one of the most confusing—and wonderful—principles of physics.
Light is radiant energy, usually referring to electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight.[1] 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.[2][3] 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[4][5] to as broadly as 380 to 800 nm.[6][7] Under ideal laboratory conditions, people can see infrared up to at least 1050 nm,[8] children and young adults ultraviolet down to about 310 to 313 nm.[9][10][11]
Primary properties of visible light are intensity, propagation direction, frequency or wavelength spectrum, and polarisation, while its speed in a vacuum, 299,792,458 meters per second, is one of the fundamental constants of nature. Visible light, as with all types of electromagnetic radiation (EMR), is experimentally found to always move at this speed in vacuum.[citation needed]
In common with all types of