Visible light

Visible light is the range of wavelengths of electromagnetic radiation perceived as colour by a human observer.

  • Visible light is a form of electromagnetic radiation.
  • The range of wavelengths that produce visible light is a very small part of the electromagnetic spectrum.
  • Other forms of electromagnetic radiation include radio waves, microwaves, infrared, ultraviolet, X-rays, and gamma rays.
  • Visible light is perceived by a human observer as all the spectral colours between red and violet plus all the other colours that result from combining them together in different proportions.
  • The complete range of colours that can be perceived by a human observer is called the visible spectrum.

Visible light

Visible light is a form of electromagnetic radiation.

  • Visible light is the range of wavelengths of electromagnetic radiation that are perceived as colour by a human observer.
  • The range of wavelengths that produce visible light is a very small part of the electromagnetic spectrum.
  • Other forms of electromagnetic radiation include radio waves, microwaves, infrared, ultraviolet, X-rays, and gamma rays.
  • Visible light is perceived by a human observer as all the spectral colours between red and violet plus all the other colours that result from mixing them together in different proportions.
  • The complete range of colours that can be perceived by a human observer is called the visible spectrum.

Visible spectrum

The visible spectrum is the range of wavelengths of the electromagnetic spectrum that correspond with all the different colours we see in the world.

  • Human beings don’t see wavelengths of visible light, but they do see the spectral colours that correspond with each wavelength and colours produced when different wavelengths are combined.
  • The visible spectrum includes all the spectral colours between red and violet and each is produced by a single wavelength.
  • The visible spectrum is often divided into named colours, though any division is somewhat arbitrary.
  • Traditional colours in English include: red, orange, yellow, green, blue, and violet.
  • The visible spectrum is continuous, and the human eye can distinguish many thousands of spectral colours.
  • The fact that we see distinct bands of colour in a rainbow is an artefact of human colour vision.
  • The visible spectrum is a small part of the electromagnetic spectrum.

https://en.wikipedia.org/wiki/Visible_spectrum

Visible spectrum

The visible part of the electromagnetic spectrum is called the visible spectrum.

  • The visible spectrum is the range of wavelengths of the electromagnetic spectrum that correspond with all the different colours we see in the world.
  • As light travels through the air it is invisible to our eyes.
  • Human beings don’t see wavelengths of light, but they do see the spectral colours that correspond with each wavelength and colours produced when different wavelengths are combined.
  • The visible spectrum includes all the spectral colours between red and violet and each is produced by a single wavelength.
  • The visible spectrum is often divided into named colours, though any division of this kind is somewhat arbitrary.
  • Traditional colours referred to in English include red, orange, yellow, green, blue, and violet.

Visual perception

Visual perception is the human ability to see and interpret the surrounding environment because of the sensitivity of the eyes to wavelengths of light corresponding to all the colours we see between red and violet.

  • The human eye and so human visual perception are tuned to the visible spectrum and so to colours between red and violet. Light, however, is rarely of a single wavelength, so an observer will usually be exposed to a range of different wavelengths of light or a mixture of wavelengths from different areas of the spectrum.
  • There are no properties of electromagnetic radiation that distinguish visible light from other parts of the electromagnetic spectrum.
  • Visual perception is associated with eyesight but also usually refers to the brain’s ability to make sense of what our eyes see.
  • The human eye and so human vision are tuned to the visible part of the electromagnetic spectrum.
  • Colour is not a property of electromagnetic radiation, but a feature of the visual perception of an observer.
  • Colour is what human beings see in the presence of light.
  • Objects appear to be different colours to an observer depending on the wavelengths, frequencies and amplitude of light at the moment it strikes the retina at the back of the eye.

Visual perception

Colour is not a property of electromagnetic radiation, but a feature of visual perception by an observer.

Wave cycle

A wave-cycle refers to the path of a wave measured from any point through the course of a single oscillation to the same point on the next oscillation.

  • Imagine a wave-cycle as a series of points marked on the path of the wave between one crest and the next.
  • All electromagnetic waves share features such as crests, troughs, oscillations, wavelength, frequency, amplitude, direction of travel.
  • As a wave oscillates (vibrates), it can be viewed as a series of individual oscillations measured from one crest to the next crest, one trough to the next trough, or from the start of a wave-cycle to the next starting point.
  • Whilst wave-cycle refers to the path from one point on a wave during a single oscillation to the same point on completion of that oscillation, wavelength is a measurement of the same phenomenon along the axis of the wave.

http://www.imagewheel.org/knowledge-base/wave-cycles/

Wave-cycle

A wave-cycle refers to the path of a wave measured from any point through the course of a single oscillation to the same point on the next oscillation.

  • Imagine a wave-cycle as a series of points marked on the path of the wave between one crest and the next.
  • All electromagnetic waves share features such as crests, troughs, oscillations, wavelength, frequency, amplitude, direction of travel.
  • Whilst a wave-cycle is the path from one point on a wave during a single oscillation to the same point on completion of that oscillation, wavelength is a measurement of the same phenomenon along the axis of the wave.

http://www.imagewheel.org/knowledge-base/wave-cycles/

Wavelength

Wavelength is a measurement from any point on the path of a wave to the same point on its next oscillation. The measurement is made parallel to the centre-line of the wave.

Wavelength can be measured from any point on a wave. To avoid confusion, it is best to measure wavelength from the top of a crest to the top of the next crest, or from the bottom of a trough to the bottom of the next trough so that the measurement is of the length of a single complete oscillation.

The wavelength of an electromagnetic wave is measured in metres.

Each type of electromagnetic radiation, such as radio waves, visible light and gamma waves,  forms a band of wavelengths on the electromagnetic spectrum.

The greater the energy, the larger the frequency and the shorter (smaller) the wavelength. Given the relationship between wavelength and frequency — the higher the frequency, the shorter the wavelength — it follows that short wavelengths are more energetic than long wavelengths.

The visible part of the electromagnetic spectrum is composed of the range of wavelengths that correspond with all the different colours we see in the world.

Human beings don’t see wavelengths of visible light, but they do see the spectral colours that correspond with each wavelength and the other colours produced when different wavelengths are combined.

The visible spectrum includes all the spectral colours between red and violet and each is produced by a single wavelength of light.

The wavelength of visible light is measured in nanometres.

The wavelength of visible light is measured in nanometres. There are 1,000,000,000 nanometres in a metre.

The visible spectrum is often divided into named colours, though any division is somewhat arbitrary.

Traditional colour names in English include red, orange, yellow, green, blue, and violet. But the visible spectrum is, in fact, continuous, and the human eye can distinguish many thousands of intermediary spectral colours.

Wavelengths corresponding with the colours of the visible spectrum are usually measured in nanometres. There are therefore 300 different colours between 400 nanometres (violet) and 700 nanometres (red). But if picometres are used instead, then there are 300,000 different wavelengths each of which corresponds with a different colour.

The perceived colour (hue) of a light stimulus depends on its wavelength.

A colour produced by a single wavelength is called a pure spectral colour.

Light is rarely of a single wavelength. Light is usually a mixture of several different wavelengths.

The greater number of spectral colours associated with a light source, the lower the saturation, so light of mixed wavelengths produces duller more neutral colours.

https://en.wikipedia.org/wiki/Wavelength

Wavelength

Wavelength is a measurement from any point on the path of a wave to the same point on its next oscillation. The measurement is made parallel to the centre-line of the wave.

  • Wavelength is a measurement from a point on the path of a wave to the same point on its next oscillation.
  • The wavelength of an electromagnetic wave is measured in metres.
  • Each type of electromagnetic radiation, such as radio waves, visible light and gamma waves, forms a band of wavelengths on the electromagnetic spectrum.
  • The visible part of the electromagnetic spectrum is composed of the range of wavelengths that correspond with all the different colours we see in the world.
  • Human beings don’t see wavelengths of visible light, but they do see the spectral colours that correspond with each wavelength and the other colours produced when different wavelengths are combined.
  • The wavelength of visible light is measured in nanometres. There are 1,000,000,000 nanometres in a metre.
  • The perceived colour (hue) of a light stimulus depends on its wavelength.
  • A colour produced by a single wavelength is called a pure spectral colour.
  • Light is rarely of a single wavelength. Light is usually a mixture of several different wavelengths.

Wave-particle duality

Wave–particle duality is the concept in quantum mechanics that every particle can be partly described in terms of particles, but also in terms of waves.

  • The dual wave-like and particle-like nature of light is known as the wave-particle duality.
    • Electromagnetic radiation is often described in terms of waves. However, the energy imparted by these waves is absorbed at single locations the way particles are absorbed.
    • The absorbed energy of an electromagnetic wave is called a photon and represents the quanta of light.
    • When a wave of light is absorbed as photons, the energy of the wave collapses to specific locations, and these locations are where the photons “arrive”. This is called the wave function collapse.
  • Albert Einstein wrote:

It seems as though we must use sometimes the one theory and sometimes the other, while at times we may use either. We are faced with a new kind of difficulty. We have two contradictory pictures of reality; separately neither of them fully explains the phenomena of light, but together they do.

https://en.wikipedia.org/wiki/Wave%E2%80%93particle_duality

White light

White light is the name given to visible light that contains all wavelengths of the visible spectrum at equal intensities.

  • The sun emits white light because sunlight contains equal amounts of all of the wavelengths of the visible spectrum.
  • As light travels through a vacuum or a medium it is described as white light if it contains all the wavelengths of visible light.
  • As light travels through the air it is invisible to our eyes.
  • White light is what an observer sees when all the colours that make up the visible spectrum strike a white or neutral coloured surface.
  • The eye also sees white when the wavelengths of light corresponding with the three primary colours red, green and blue (RGB) are projected onto a neutrally coloured surface.
  • Light is only visible as it is emitted by an object such as an electrical filament or when it strikes an object.
  • White light appears coloured when some wavelengths of light are reflected by the surface of an object but others are absorbed.
  • Artificial light sources typically emit light with an uneven distribution of wavelengths or intensities.
  • Whilst there is no single, unique specification of “white light”, there is indeed a unique specification of “white object”, or, more specifically, “white surface”.
  • A perfectly white surface diffusely reflects (scatters) all visible light that strikes it, without absorbing any, irrespective of the light’s wavelength or spectral distribution.
  • Since it does not absorb any of the incident light, white is the lightest possible colour. If the reflection is not diffuse but rather specular, this describes a mirror rather than a white surface.
  • Reflection of 100% of incident light at all wavelengths is a form of uniform reflectance, so white it is an achromatic colour, meaning a colour without hue.

https://en.wikipedia.org/wiki/White

White light

White light is the name given to visible light that contains all wavelengths of the visible spectrum at equal intensities.

  • As light travels through a vacuum or a medium it is described as white light if it contains all the wavelengths of visible light.
  • As light travels through the air it is invisible to our eyes.
  • When we look around we see through the air because it is very transparent and light passes through it.
  • The term white light doesn’t mean light is white as it travels through the air.
  • One situation in which light becomes visible is when it reflects off the surface of an object.
  • When white light strikes a neutral coloured object and all wavelengths are reflected then it appears white to an observer.