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Rainbows as Superimposed Cones of Colour

Look carefully at the diagram at the top of the page. Now check out the following questions (and answers)!Introducing the diagram! Read back and forward between the image at the top of the page and the explanation below!

Follow the blue links for definitions . . . . or check the summaries of key terms below!

Move to the next level! Check out the following terms.

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Rainbows as Superimposed Disks of Colour

Look carefully at the diagram at the top of the page. Now check out the following questions (and answers)!Introducing the diagram! Read back and forward between the image at the top of the page and the explanation below!

Follow the blue links for definitions . . . . or check the summaries of key terms below!

Move to the next level! Check out the following terms.

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Drawing Rainbow Diagrams

Look carefully at the diagram at the top of the page. Now check out the following questions (and answers)!Introducing the diagram! Read back and forward between the image at the top of the page and the explanation below!

Follow the blue links for definitions . . . . or check the summaries of key terms below!

Move to the next level! Check out the following terms.

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Intensity of Rainbow Colours

Look carefully at the diagram at the top of the page. Now check out the following questions (and answers)!Introducing the diagram! Read back and forward between the image at the top of the page and the explanation below!

Follow the blue links for definitions . . . . or check the summaries of key terms below!

Move to the next level! Check out the following terms.

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The Position of Each Raindrop Determines its Colour

Look carefully at the diagram at the top of the page. Now check out the following questions (and answers)!Introducing the diagram! Read back and forward between the image at the top of the page and the explanation below!

Follow the blue links for definitions . . . . or check the summaries of key terms below!

Move to the next level! Check out the following terms.

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The Position of Raindrops Determine Their Colour

Look carefully at the diagram at the top of the page. Now check out the following questions (and answers)!Introducing the diagram! Read back and forward between the image at the top of the page and the explanation below!

Follow the blue links for definitions . . . . or check the summaries of key terms below!

Move to the next level! Check out the following terms.

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Sunlight as Light Source

Look carefully at the diagram at the top of the page. Now check out the following questions (and answers)!Introducing the diagram! Read back and forward between the image at the top of the page and the explanation below!

Follow the blue links for definitions . . . . or check the summaries of key terms below!

Move to the next level! Check out the following terms.

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The Path of Red Ray Through a Raindrop in Detail

Look carefully at the diagram at the top of the page. Now check out the following questions (and answers)!Introducing the diagram! Read back and forward between the image at the top of the page and the explanation below!

Follow the blue links for definitions . . . . or check the summaries of key terms below!

Move to the next level! Check out the following terms.

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Reflection and Refraction in a Raindrop

Look carefully at the diagram at the top of the page. Now check out the following questions (and answers)!Introducing the diagram! Read back and forward between the image at the top of the page and the explanation below!

Follow the blue links for definitions . . . . or check the summaries of key terms below!

Move to the next level! Check out the following terms.

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Dispersion of White Light in a Raindrop

Look carefully at the diagram at the top of the page. Now check out the following questions (and answers)!Introducing the diagram! Read back and forward between the image at the top of the page and the explanation below!

Follow the blue links for definitions . . . . or check the summaries of key terms below!

Move to the next level! Check out the following terms.

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Reflection and Refraction in a Raindrop

Look carefully at the diagram at the top of the page. Now check out the following questions (and answers)!Introducing the diagram! Read back and forward between the image at the top of the page and the explanation below!

Follow the blue links for definitions . . . . or check the summaries of key terms below!

Move to the next level! Check out the following terms.

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Angular Distance Determines Raindrop Colour

Look carefully at the diagram at the top of the page. Now check out the following questions (and answers)!Introducing the diagram! Read back and forward between the image at the top of the page and the explanation below!

Follow the blue links for definitions . . . . or check the summaries of key terms below!

Move to the next level! Check out the following terms.

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The Apparent Position of a Rainbow

Look carefully at the diagram at the top of the page. Now check out the following questions (and answers)!Introducing the diagram! Read back and forward between the image at the top of the page and the explanation below!

Follow the blue links for definitions . . . . or check the summaries of key terms below!

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The Angle Between Incident and Refracted Rays

Look carefully at the diagram at the top of the page. Now check out the following questions (and answers)!Introducing the diagram! Read back and forward between the image at the top of the page and the explanation below!

Follow the blue links for definitions . . . . or check the summaries of key terms below!

Move to the next level! Check out the following terms.

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Rainbows Appear as Bands of Spectral Colour

Look carefully at the diagram at the top of the page. Now check out the following questions (and answers)!Introducing the diagram! Read back and forward between the image at the top of the page and the explanation below!

Follow the blue links for definitions . . . . or check the summaries of key terms below!

Move to the next level! Check out the following terms.

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The Higher the Sun, the Lower the Rainbow

Look carefully at the diagram at the top of the page. Now check out the following questions (and answers)!Introducing the diagram! Read back and forward between the image at the top of the page and the explanation below!

Follow the blue links for definitions . . . . or check the summaries of key terms below!

Move to the next level! Check out the following terms.

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The Lower the Sun, the Higher the Rainbow

Look carefully at the diagram at the top of the page. Now check out the following questions (and answers)!Introducing the diagram! Read back and forward between the image at the top of the page and the explanation below!

Follow the blue links for definitions . . . . or check the summaries of key terms below!

Move to the next level! Check out the following terms.

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Sun, Observer and Rainbow Share a Common Axis

Look carefully at the diagram at the top of the page. Now check out the following questions (and answers)!Introducing the diagram! Read back and forward between the image at the top of the page and the explanation below!

Follow the blue links for definitions . . . . or check the summaries of key terms below!

Move to the next level! Check out the following terms.

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A Rainbow is an Optical Phenomenon

Look carefully at the diagram at the top of the page. Now check out the following questions (and answers)!Introducing the diagram! Read back and forward between the image at the top of the page and the explanation below!

Follow the blue links for definitions . . . . or check the summaries of key terms below!

Move to the next level! Check out the following terms.

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Rainbows Seen From the Ground Form an Arc

Look carefully at the diagram at the top of the page. Now check out the following questions (and answers)!Introducing the diagram! Read back and forward between the image at the top of the page and the explanation below!

Follow the blue links for definitions . . . . or check the summaries of key terms below!

Move to the next level! Check out the following terms.

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Rainbows Seen From the Air Form a Circle

Look carefully at the diagram at the top of the page. Now check out the following questions (and answers)!Introducing the diagram! Read back and forward between the image at the top of the page and the explanation below!

Follow the blue links for definitions . . . . or check the summaries of key terms below!

Move to the next level! Check out the following terms.

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How to See a Rainbow

Look carefully at the diagram at the top of the page. Now check out the following questions (and answers)!Introducing the diagram! Read back and forward between the image at the top of the page and the explanation below!

Follow the blue links for definitions . . . . or check the summaries of key terms below!

Move to the next level! Check out the following terms.

...

Take a Photo of a Rainbow

Look carefully at the diagram at the top of the page. Now check out the following questions (and answers)!Introducing the diagram! Read back and forward between the image at the top of the page and the explanation below!

Follow the blue links for definitions . . . . or check the summaries of key terms below!

Move to the next level! Check out the following terms.

...
Sensitivity of Eye to the Colour Spectrum (svg) 11000-0-A-BL-EN

Sensitivity of Eye to the Colour Spectrum

This diagram is a new addition to the site! More information will be added ASAP 🙂

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Chromatic Dispersion of Red Green and Blue Wavelengths

Chromatic Dispersion of Red Green and Blue Wavelengths

The diagram shows an incident ray of white light composed of wavelengths corresponding with red, green and blue wavelengths approaching the boundary between air and glass.
  • As the ray crosses the boundary into the glass each wavelength bends towards the normal (the dotted green line) by a different amount.
  • The incident ray of light is refracted towards the normal because the ray travels from air, the faster, less optically dense medium with a smaller refractive index into the glass, a slower, more optically dense medium with the higher refractive index.
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RGB Colour Wheel with 6 Colours

RGB Colour Wheel with 6 Colours

This is one of a series of diagrams exploring RGB colour wheels. Colour wheels demonstrate or simulate the effect of colour mixing.
Colour wheels can be used to explore the effect of mixing any type of colour. Light, inks, dyes, artist's paints, pigments and colourants all produce other colours when mixed together. Whilst a colour model outlines a method for mixing and using different types of colour, a colour wheel explores what happens in practice ...
HSB Additive Colour Model

HSB Additive Colour Model

This diagram is a new addition to the site! More information will be added ASAP 🙂 ...
HSB Colour Model: Hue and Brightness

HSB Colour Model: Hue and Brightness

This diagram is a new addition to the site! More information will be added ASAP 🙂 ...
Greyscale: Disks

Greyscale: Disks

This diagram is a new addition to the site! More information will be added ASAP 🙂 ...
HSB Greyscale: Wedges

HSB Greyscale: Wedges

This diagram is a new addition to the site! More information will be added ASAP 🙂 ...
Refractive Index Explained

Refractive Index Explained

The diagram demonstrates the direct relationship between the speed of light as it travels through a vacuum (c) and the speed of light as it travels through any other transparent medium (v).
  • Because the speed of light in a vacuum is always the same, the formula can be used to calculate:
    • The refractive index (n) of a medium if the speed of light through the medium (v) is known.
    • The speed of light in a medium (v) if its refractive index (n) is known
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Refraction, Reflection and Total Internal Reflection

Refraction, Reflection and Total Internal Reflection

This diagram is a new addition to the site! More information will be added ASAP 🙂 ...
Response of the Cone Cells in the Human Eye to Colour (svg) 11010-0-A-BL-EN

Response of the Cone Cells in the Human Eye to Colour

This diagram is a new addition to the site! More information will be added ASAP 🙂 ...
How to Use the Refractive Index of a Medium

How to Use the Refractive Index of a Medium

The diagram explains how to use the refractive index (sometimes called the index of refraction) of a medium to calculate the speed at which light will travels through it.
  • The refractive index of a medium is defined as the speed of light in a vacuum (c) divided by the speed of light in a medium (v).
...
RGB Colour Wheel with 6 Colours

RGB Colour Wheel with 6 Colours

This is one of a series of diagrams exploring RGB colour wheels. Colour wheels demonstrate or simulate the effect of colour mixing.
Colour wheels can be used to explore the effect of mixing any type of colour. Light, inks, dyes, artist's paints, pigments and colourants all produce other colours when mixed together. Whilst a colour model outlines a method for mixing and using different types of colour, a colour wheel explores what happens in practice ...
RYB Subtractive Colour Model

RYB Subtractive Colour Model

This diagram introduces the RYB colour model. It shows the three primary colours (red, yellow and blue) with secondary colours between them.
The RYB colour model is a subtractive colour model that predicts the appearance of red, yellow and blue paints and opaque pigments when they are mixed together to produce other colours. What you need to remember:
  • The RYB colour model is a method for mixing different artists paints and opaque pigments to produce other colours. It is called a subtractive colour model (a subtractive approach to colour).
  • The name of the RYB colour model comes from ...
HSB Colour Model: Hue and Saturation

HSB Colour Model: Hue and Saturation

This diagram is a new addition to the site! More information will be added ASAP 🙂 ...
256 RGB Colours: Blue to Magenta

256 RGB Colours: Blue to Magenta

This is one of a series of six diagrams that together show all 1530 fully saturated colours in the RGB colour model. Fully saturated colours are produced by mixing two primary colours together.
Each diagram shows 256 colours starting with a primary and finishing with a secondary colour or visa-vera:
  • Red (primary colour) to yellow (secondary colour)
  • Yellow (secondary) to green (primary)
  • Green (primary) to cyan (secondary)
  • Cyan (secondary) to blue (primary)
  • Blue (primary) to magenta (secondary)
  • Magenta (secondary) to red (primary)
...
Facts about the Sun

Facts about the Sun

This diagram introduces the Sun, the star at the centre of our solar system. It lists some useful facts that help explain why it is so important in our lives.
Remember that:
  • The sun is unlike anything else in our experience. Its age, size, temperature are all on a scale apart from life on planet Earth.
  • It explodes with the force of a billion one-megaton nuclear bombs every single second of every single day.
  • Without the energy produced by the sun, life as we know it would not be possible.
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Reflection of a Ray of Light

Reflection of a Ray of Light

The diagram shows an incident ray of light approaching the boundary between air and glass.
  • When the ray strikes the boundary between air and glass it bounces off the surface of the glass because it is highly reflective.
  • The diagram demonstrates that the angle of incidence and angle of reflection are the same.
  • The angles of incidence and reflection are both measured between the ray and the normal (the dotted green line).
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Refraction of Light Towards the Normal

Refraction of Light Towards the Normal

The diagram shows an incident ray of white light approaching the boundary between air and glass.
  • As the ray crosses the boundary and encounters the glass it bends towards the normal (the dotted green line).
  • The incident ray of light is refracted towards the normal because the ray travels from air, the faster, less optically dense medium with a lower refractive index into the glass, a slower, more optically dense medium with the higher refractive index.
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Combining Red, Green and Blue Light

Combining Red, Green and Blue Light

This diagram explains what happens when red, green and blue primary colours are projected onto a dark surface so that they overlap.
What you need to remember:
  • Mixing different wavelengths of light to produce other colours, is called an additive colour model or an additive approach to colour.
  • Red, green and blue (RGB) are additive primary colours. This means that when these wavelengths of light are projected onto a dark surface they combined to produce other colours.
  • If wavelengths of light corresponding with all three additive primary colours are projected in equal amounts onto a dark surface the ...
Prism Splits a Ray of Light into Spectral Colours (svg) 06700-0-A-BL-EN

Prism Splits a Ray of Light into Spectral Colours

In this diagram a ray of incident light strikes one of the three rectangular surfaces at an angle so that it exits from the middle of another.
  • The light source used produces white light which is focused into a narrow beam.
  • As the ray enters the prism the angles of incidence and refraction are the same.
  • When the light exits the prism the angles of incidence and refraction are the same.
...
Overlapping Beams of Cyan, Magenta and Yellow

Overlapping Beams of Cyan, Magenta and Yellow

This diagram shows the effect of projecting cyan, magenta and yellow light onto a neutral coloured surface.
  • In the RGB colour model, cyan, magenta and yellow are secondary colours. Notice what colours are produced where they overlap!
  • Imagine that the three circles of colour (cyan, magenta and yellow) are produced by torches shining beams of light so they overlap one another.
  • Overlapping pairs of primary colours produce secondary colours.
  • But in this diagram overlapping pairs of secondary colours produce primary colours
  • The area where all three primary colours overlap is white.
Understanding the diagram
  • The diagrams illustrate ...
256 RGB Colours: Cyan to Blue

256 RGB Colours: Cyan to Blue

This is one of a series of six diagrams that together show all 1530 fully saturated colours in the RGB colour model. Fully saturated colours are produced by mixing two primary colours together.
Each diagram shows 256 colours starting with a primary and finishing with a secondary colour or visa-vera:
  • Red (primary colour) to yellow (secondary colour)
  • Yellow (secondary) to green (primary)
  • Green (primary) to cyan (secondary)
  • Cyan (secondary) to blue (primary)
  • Blue (primary) to magenta (secondary)
  • Magenta (secondary) to red (primary)
...
HSB Colour Model: Hue and Brightness

HSB Colour Model: Hue and Brightness

This diagram is a new addition to the site! More information will be added ASAP 🙂 ...
256 RGB Colours: Magenta to Red

256 RGB Colours: Magenta to Red

This is one of a series of six diagrams that together show all 1530 fully saturated colours in the RGB colour model. Fully saturated colours are produced by mixing two primary colours together.
Each diagram shows 256 colours starting with a primary and finishing with a secondary colour or visa-vera:
  • Red (primary colour) to yellow (secondary colour)
  • Yellow (secondary) to green (primary)
  • Green (primary) to cyan (secondary)
  • Cyan (secondary) to blue (primary)
  • Blue (primary) to magenta (secondary)
  • Magenta (secondary) to red (primary)
...
RGB Colour Wheel with 3 Colours

RGB Colour Wheel with 3 Colours

This is one of a series of diagrams exploring RGB colour wheels. Colour wheels demonstrate or simulate the effect of colour mixing.
Colour wheels can be used to explore the effect of mixing any type of colour. Light, inks, dyes, artist's paints, pigments and colourants all produce other colours when mixed together. Whilst a colour model outlines a method for mixing and using different types of colour, a colour wheel explores what happens in practice ...
Light strikes Curved Surface in Line with the Normal

Light strikes Curved Surface in Line with the Normal

The diagram shows an incident ray of light approaching the boundary between air and glass.
  • When the ray strikes the boundary between air and glass some of the light bounces off the surface of the glass because it is highly reflective.
  • The diagram demonstrates that the angle of incidence and angle of reflection are the same.
  • The angles of incidence and reflection are both measured between the ray and the normal (the dotted green line).
...
Human Eye in Cross Section

Human Eye in Cross Section

This diagram is a new addition to the site! More information will be added ASAP 🙂 ...
Spectral Colour and the RGB Colour Model

Spectral Colour and the RGB Colour Model

This diagram shows six spectral colours, red, orange, yellow, green, blue and violet. 
  • Spectral colours are produced by a single wavelength of light.
  • Some spectral colours can also be produced by mixing two wavelengths of light together.
Understanding the diagram:
  • Above the line of coloured circles are the wavelengths of light that produce each spectral colour.
  • Of the six colours (ROYGBV), red, green and blue can only be produced by a single wavelength of light.
  • The other three spectral colours, orange, yellow and violet, can be produced either by a single wavelength of light or by additive ...
Long Waves to Short Waves

Long Waves to Short Waves

This diagram shows six electromagnetic waves. Each wave corresponds with a colour within the visible spectrum that an observer might recognise.
Remember that:
  • Electromagnetic waves, which are a form of electromagnetic radiation, propagating from a light source, travel through space and encounter different materials.
  • Colour is not a property of electromagnetic radiation, but an aspect of visual perception.
  • A human observer can distinguish between colours corresponding with many thousands of wavelengths of light in the visible spectrum. These colours are often called spectral colours.
  • The largest part of the electromagnetic spectrum is outside the wavelengths of visible light ...
Combining Different Wavelengths of Light to make White

Combining Different Wavelengths of Light to make White

This diagram looks at three situations in which an observer will see white light reflected off a dark surface.
Three different light sources are shown in the diagram.
  • Each light source produces a different combination of wavelengths and each wavelength has the same intensity.
  • The light source at the top of the diagram contains three component colours: RGB (red, green, blue).
  • The light source on the left contains six component colours - ROYGBV (red, orange, yellow, green, blue and violet).
  • The light source on the right contains a continuous spectrum of wavelengths which means it contains many thousands ...
256 RGB Colours: Yellow to Green

256 RGB Colours: Yellow to Green

This is one of a series of six diagrams that together show all 1530 fully saturated colours in the RGB colour model. Fully saturated colours are produced by mixing two primary colours together.
Each diagram shows 256 colours starting with a primary and finishing with a secondary colour or visa-vera:
  • Red (primary colour) to yellow (secondary colour)
  • Yellow (secondary) to green (primary)
  • Green (primary) to cyan (secondary)
  • Cyan (secondary) to blue (primary)
  • Blue (primary) to magenta (secondary)
  • Magenta (secondary) to red (primary)
...
RGB and HSB Colour Values

RGB and HSB Colour Values

This diagram is a new addition to the site! More information will be added ASAP 🙂 ...
1530 RGB Colours

1530 RGB Colours

This diagram shows all 1530 fully saturated colours in the RGB colour model. 
The diagram splits the total of 1530 into blocks of 256 colours with each block starting with a primary and finishing with a secondary colour or visa-vera. The six segments are:
  • Red (primary colour) to yellow (secondary colour)
  • Yellow (secondary) to green (primary)
  • Green (primary) to cyan (secondary)
  • Cyan (secondary) to blue (primary)
  • Blue (primary) to magenta (secondary)
  • Magenta (secondary) to red (primary)
...
Ray of Light Strikes Surface at a Right Angle

Ray of Light Strikes Surface at a Right Angle

The diagram shows an incident ray of light approaching the boundary between air and glass.
  • When the ray strikes the boundary between air and glass partial reflection and partial refraction takes place. This means that a proportion of the light bounces off the surface of the glass and returns into the air whilst the rest undergoes refraction.
  • In this diagram, the incident ray of light approaches the boundary between air and glass at an angle of incidence is 00.
  • The reflected ray bounces off the surface in line with the incident ray, at a 00 angle to the normal.
  • The refracted ...
Human Eye in Cross Section

Human Eye in Cross Section

This diagram is a new addition to the site! More information will be added ASAP 🙂 ...
Spectral and RGB Colour

Spectral and RGB Colour

This diagram shows the six spectral colours associated with the colours of the rainbow.
  • The top half of the diagram shows that each of these spectral colours can be produced by a single wavelength of light.
  • The bottom half of the diagram shows that three spectral colours (red, green and blue) can be combined in pairs to produce orange, yellow and violet.
Remember that:
  • Spectral colours are produced by a single wavelength of light. So each individual wavelength of visible light produces a different spectral colour.
  • Rainbows are produced by spectral colours as sunlight is refracted and ...
Why an Object Appears White in Sunlight

Why an Object Appears White in Sunlight

This is one of a set of 10 diagrams exploring why objects appear to be different colours to an observer.
There are always three key factors that affect the colour of an object.
  • The first is the type of light source and what happens to the light on its journey towards an object.
  • The second is what happens when light strikes different types of objects and materials.
  • The third concerns factors related to the observer which affect what they see and how things appear.
...
Adding RGB Colours between Primaries

Adding RGB Colours between Primaries

This diagram is brand new! A full explanation will be added ASAP 🙂

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256 RGB Colours: Green to Cyan

256 RGB Colours: Green to Cyan

This is one of a series of six diagrams that together show all 1530 fully saturated colours in the RGB colour model. Fully saturated colours are produced by mixing two primary colours together.
Each diagram shows 256 colours starting with a primary and finishing with a secondary colour or visa-vera:
  • Red (primary colour) to yellow (secondary colour)
  • Yellow (secondary) to green (primary)
  • Green (primary) to cyan (secondary)
  • Cyan (secondary) to blue (primary)
  • Blue (primary) to magenta (secondary)
  • Magenta (secondary) to red (primary)
...
Hue and Greyscale

Hue and Greyscale

This diagram is a new addition to the site! More information will be added ASAP 🙂 ...
256 RGB Colours Between Red and Yellow

256 RGB Colours Between Red and Yellow

This is one of a series of six diagrams that together show all 1530 fully saturated colours in the RGB colour model.
Each diagram shows 256 colours starting with a primary and finishing with a secondary colour or visa-vera:
  • Red (primary colour) to yellow (secondary colour)
  • Yellow (secondary) to green (primary)
  • Green (primary) to cyan (secondary)
  • Cyan (secondary) to blue (primary)
  • Blue (primary) to magenta (secondary)
  • Magenta (secondary) to red (primary)
...
Refraction and Dispersion of a Ray of White Light

Refraction and Dispersion of a Ray of White Light

The diagram illustrates chromatic dispersion:
  • Chromatic dispersion is often simply called dispersion.
  • The text below the image explains that dispersion takes place because the refractive index of the glass is different for each wavelength of light (ROYGBV).
  • Chromatic dispersion takes place because the refractive index of the glass is different for each wavelength.
  • White light containing all wavelengths of the visible spectrum disperses into a rainbow of colours.
...
Retina of the Human Eye in Detail

Retina of the Human Eye in Detail

This diagram is a new addition to the site! More information will be added ASAP 🙂 ...
The Human Eye and RGB Colour

The Human Eye and RGB Colour

This diagram is about the perception of colour. It explores how our eyes respond to wavelengths of light corresponding with red, green and blue.
  • As we look at the world on a sunny day a vast range of wavelengths of visible light enter our eyes. Each wavelength corresponds with the perception of a different spectral colour.
  • When wavelengths of light corresponding with only red, green and blue enter the eye in different proportions, our eyes are still able to see a full gamut of colours.
  • The colours we see when wavelengths corresponding with just red, green and blue light ...
Why an Object Appears Orange in Sunlight

Why an Object Appears Orange in Sunlight

This is one of a set of 10 diagrams exploring why objects appear to be different colours to an observer.
There are always three key factors that affect the colour of an object.
  • The first is the type of light source and what happens to the light on its journey towards an object.
  • The second is what happens when light strikes different types of objects and materials.
  • The third concerns factors related to the observer which affect what they see and how things appear.
...
RGB Colour Wheel with 3 Colours

RGB Colour Wheel with 3 Colours

This is one of a series of diagrams exploring RGB colour wheels. Colour wheels demonstrate or simulate the effect of colour mixing.
Colour wheels can be used to explore the effect of mixing any type of colour. Light, inks, dyes, artist's paints, pigments and colourants all produce other colours when mixed together. Whilst a colour model outlines a method for mixing and using different types of colour, a colour wheel explores what happens in practice ...
256 RGB Colours: Red to Yellow

256 RGB Colours: Red to Yellow

This is one of a series of six diagrams that together show all 1530 fully saturated colours in the RGB colour model. Fully saturated colours are produced by mixing two primary colours together.
Each diagram shows 256 colours starting with a primary and finishing with a secondary colour or visa-vera:
  • Red (primary colour) to yellow (secondary colour)
  • Yellow (secondary) to green (primary)
  • Green (primary) to cyan (secondary)
  • Cyan (secondary) to blue (primary)
  • Blue (primary) to magenta (secondary)
  • Magenta (secondary) to red (primary)
...
RGB Colour Wheels with 3 to 102 Colours

RGB Colour Wheels with 3 to 102 Colours

This diagram is a new addition to the site! More information will be added ASAP 🙂 ...
RGB Colour Picker: Red to Yellow

RGB Colour Picker: Red to Yellow

This is one of a series of six colour pickers that together show all 1530 fully saturated RGB colours along with their codes. 
Each diagram shows 256 colours starting with a primary and finishing with a secondary colour or visa-vera:
  • Red (primary colour) to yellow (secondary colour)
  • Yellow (secondary) to green (primary)
  • Green (primary) to cyan (secondary)
  • Cyan (secondary) to blue (primary)
  • Blue (primary) to magenta (secondary)
  • Magenta (secondary) to red (primary)
...
Electromagnetic spectrum

Electromagnetic spectrum

This diagram shows that the electromagnetic spectrum includes waves with all possible wavelengths, ranging from low energy radio waves through visible light to high energy gamma rays.
  • Notice that a wave with a longer wavelength has a lower frequency and carries less energy.
  • Notice that a wave with a shorter wavelength has a higher frequency and carries more energy.
Remember that:
  • The electromagnetic spectrum includes, in order of increasing frequency and decreasing wavelength: radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays.
  • There are no precisely defined boundaries between the bands of electromagnetic ...
Human Eye Eyeball and Retina

Human Eye Eyeball and Retina

This diagram is a new addition to the site! More information will be added ASAP 🙂 ...
Why an Object Appears Red in Sunlight

Why an Object Appears Red in Sunlight

This is one of a set of 10 diagrams exploring why objects appear to be different colours to an observer.
There are always three key factors that affect the colour of an object.
  • The first is the type of light source and what happens to the light on its journey towards an object.
  • The second is what happens when light strikes different types of objects and materials.
  • The third concerns factors related to the observer which affect what they see and how things appear.
...
Red light Projected onto a Dark Surface

Red light Projected onto a Dark Surface

This is one of a set of 3 diagrams showing torches projecting red, green and blue light onto a neutral coloured surface.
A fourth diagram shows what happens when all three torches are turned on at the same time and their beams partially overlap one another. Understanding the diagrams:
  • The diagrams illustrate how the RGB colour model works in practice.
  • Each torch emits light at the same intensity.
  • Each torch points towards a different area of the surface.
  • The light in each case is of a single wavelength so produces a spectral colour.
  • The selected wavelengths are: red ...
Why-an-Object-Appears-Green-in-Sunlight (svg) 02000-0-A-BL-EN

Why an Object Appears Green in Sunlight

This is one of a set of 10 diagrams exploring why objects appear to be different colours to an observer.
There are always three key factors that affect the colour of an object.
  • The first is the type of light source and what happens to the light on its journey towards an object.
  • The second is what happens when light strikes different types of objects and materials.
  • The third concerns factors related to the observer which affect what they see and how things appear.
...
RGB Colour Wheel with 18 Colours

RGB Colour Wheel with 18 Colours

This is one of a series of diagrams exploring RGB colour wheels. Colour wheels demonstrate or simulate the effect of colour mixing.
Colour wheels can be used to explore the effect of mixing any type of colour. Light, inks, dyes, artist's paints, pigments and colourants all produce other colours when mixed together. Whilst a colour model outlines a method for mixing and using different types of colour, a colour wheel explores what happens in practice ...
Paths of Red Green and Blue Rays in a Raindrop

Paths of Red Green and Blue Rays in a Raindrop

This diagram is a new addition to the site! More information will be added ASAP 🙂 ...
Colours Between RGB Primaries

Colours Between RGB Primaries

This diagram is a new addition to the site! More information will be added ASAP 🙂 ...
256 RGB Colours Between Yellow and Green

256 RGB Colours Between Yellow and Green

This is one of a series of six diagrams that together show all 1530 fully saturated colours in the RGB colour model.
Each diagram shows 256 colours starting with a primary and finishing with a secondary colour or visa-vera:
  • Red (primary colour) to yellow (secondary colour)
  • Yellow (secondary) to green (primary)
  • Green (primary) to cyan (secondary)
  • Cyan (secondary) to blue (primary)
  • Blue (primary) to magenta (secondary)
  • Magenta (secondary) to red (primary)
...
Actual and Observed Position of an Object in Water

Actual and Observed Position of an Object in Water

This diagram is a new addition to the site! More information will be added ASAP 🙂 ...
Wavelengths from Red to Violet

Wavelengths from Red to Violet

This diagram is about which wavelengths of electromagnetic radiation correspond with the different colours we see in the world.
The important fact to remember is that the wavelengths of light within the visible spectrum correspond with all the colours that we see between red and violet.
  • The white arrows in the diagram show the Sun emitting sunlight at all wavelengths of the visible spectrum.
  • The term white light is used when all colours of the visible spectrum are mixed together.
  • The spectrum of colours between red and violet illustrates that although an observer will often describe visible light ...
Green Light Projected onto a Dark Surface

Green Light Projected onto a Dark Surface

This is one of a set of 3 diagrams showing torches projecting red, green and blue light onto a neutral coloured surface.
A fourth diagram shows what happens when all three are on at the same time and their beams partially overlap one another. Understanding the diagrams:
  • The diagrams illustrate how the RGB colour model works in practice.
  • Each torch emits light at the same intensity.
  • Each torch points towards a different area of the surface.
  • The light in each case is of a single wavelength so produces a spectral colour.
  • The selected wavelengths are: red = 660 ...
Why an Object Appears Blue in Sunlight

Why an Object Appears Blue in Sunlight

This is one of a set of 10 diagrams exploring why objects appear to be different colours to an observer.
There are always three key factors that affect the colour of an object.
  • The first is the type of light source and what happens to the light on its journey towards an object.
  • The second is what happens when light strikes different types of objects and materials.
  • The third concerns factors related to the observer which affect what they see and how things appear.
...
RGB Colour Wheel with 18 Colours

RGB Colour Wheel with 18 Colours

This is one of a series of diagrams exploring RGB colour wheels. Colour wheels demonstrate or simulate the effect of colour mixing.
Colour wheels can be used to explore the effect of mixing any type of colour. Light, inks, dyes, artist's paints, pigments and colourants all produce other colours when mixed together. Whilst a colour model outlines a method for mixing and using different types of colour, a colour wheel explores what happens in practice ...
How to See a Rainbow

How to See a Rainbow

This diagram is a new addition to the site! More information will be added ASAP 🙂 ...
Adding Colours Between RGB Primaries

Adding Colours Between RGB Primaries

This diagram is a new addition to the site! More information will be added ASAP 🙂 ...
RGB Colour Picker: Yellow to Green

RGB Colour Picker: Yellow to Green

This is one of a series of six colour pickers that together show all 1530 fully saturated RGB colours along with their codes.
Each diagram shows 256 colours starting with a primary and finishing with a secondary colour or visa-vera:
  • Red (primary colour) to yellow (secondary colour)
  • Yellow (secondary) to green (primary)
  • Green (primary) to cyan (secondary)
  • Cyan (secondary) to blue (primary)
  • Blue (primary) to magenta (secondary)
  • Magenta (secondary) to red (primary)
...
Comparing Wavelengths: Radio to Gamma

Comparing Wavelengths: Radio to Gamma

This diagram compares the wavelength of four electromagnetic waves and arranges them according to their position within the electromagnetic spectrum.
  • Radio waves are shown at the top. They have the longest wavelength of the four types. These waves are shown as dull red. They are invisible to the human eye.
  • Red has the longest wavelength of the visible part of the electromagnetic spectrum.
  • Violet has the shortest wavelength of the visible part of the electromagnetic spectrum.
  • Gamma rays are shown at the bottom. They have the shortest wavelength of the four types. These waves are shown as a dull ...
The Visible Spectrum

The Visible Spectrum

This diagram is about sunlight, the visible spectrum and which wavelengths of electromagnetic radiation correspond with the different colours we see in the world.
The diagram shows that wavelengths of light within the visible spectrum correspond with the different colours we see in the world. Notice that:
  • The white arrows in the diagram represent the Sun emitting sunlight at every wavelength of the visible spectrum.
  • The term white light is used when all colours of the visible spectrum are mixed together.
  • The coloured arrows represent six bands of wavelengths of visible light corresponding with red, orange, yellow, green, ...
Blue Light Projected onto a Dark Surface

Blue Light Projected onto a Dark Surface

This is one of a set of 3 diagrams showing torches projecting red, green and blue light onto a neutral coloured surface.
A fourth diagram shows what happens when all three torches are turned on at the same time and their beams partially overlap one another. Understanding the diagrams:
  • The diagrams illustrate how the RGB colour model works in practice.
  • Each torch emits light at the same intensity.
  • Each torch points towards a different area of the surface.
  • The light in each case is of a single wavelength so produces a spectral colour.
  • The selected wavelengths are: red ...
Why an Object Appears Violet in Sunlight

Why an Object Appears Violet in Sunlight

This is one of a set of 10 diagrams exploring why objects appear to be different colours to an observer.
There are always three key factors that affect the colour of an object.
  • The first is the type of light source and what happens to the light on its journey towards an object.
  • The second is what happens when light strikes different types of objects and materials.
  • The third concerns factors related to the observer which affect what they see and how things appear.
...
RGB Colour Wheel with 30 Colours

RGB Colour Wheel with 30 Colours

This is one of a series of diagrams exploring RGB colour wheels. Colour wheels demonstrate or simulate the effect of colour mixing.
Colour wheels can be used to explore the effect of mixing any type of colour. Light, inks, dyes, artist's paints, pigments and colourants all produce other colours when mixed together. Whilst a colour model outlines a method for mixing and using different types of colour, a colour wheel explores what happens in practice ...
Spectral Colour

Spectral Colour

This diagram is a new addition to the site! More information will be added ASAP 🙂 ...
Mixing Primary Colours in Different Proportions

Mixing Primary Colours in Different Proportions

This diagram is a new addition to the site! More information will be added ASAP 🙂 ...
256 RGB Colours Between Green and Cyan

256 RGB Colours Between Green and Cyan

This is one of a series of six diagrams that together show all 1530 fully saturated colours in the RGB colour model.
Each diagram shows 256 colours starting with a primary and finishing with a secondary colour or visa-vera:
  • Red (primary colour) to yellow (secondary colour)
  • Yellow (secondary) to green (primary)
  • Green (primary) to cyan (secondary)
  • Cyan (secondary) to blue (primary)
  • Blue (primary) to magenta (secondary)
  • Magenta (secondary) to red (primary)
...
Refraction of Light Away from the Normal

Refraction of Light Away from the Normal

The diagram shows an incident ray of white light approaching the boundary between air and glass.
  • As the ray travels through the glass and then crosses the boundary and encounters air it bends away from the normal (the dotted green line).
  • The incident ray of light is refracted away from the normal because the ray travels from glass, the slower, more optically dense medium with a higher refractive index into the air, a faster, less optically dense medium with a lower refractive index.
...
Facts about White Light

Facts about White Light

This diagram introduces white light, the name given to light that contains all wavelength of the visible spectrum.
Remember that:
  • White light contains all the wavelengths of the visible spectrum.
  • White light contains all wavelengths of light that correspond with the colours of the rainbow.
  • White light does not include infrared and ultraviolet wavelengths of light.
...
Red, Green and Blue Lights Projected onto a Dark Surface

Red, Green and Blue Lights Projected onto a Dark Surface

This diagram shows the effect of projecting red, green and blue light onto a neutral coloured surface.
  • Imagine that the three circles of colour (red, green and blue) are produced by three torches shining beams of light so they overlap one another.
  • Overlapping pairs of primary colours produce secondary colours.
  • Overlapping pairs of secondary colours produce primary colours.
  • The area where all three primary colours overlap is white.
Understanding the diagram:
  • The diagrams illustrate how the RGB colour model works in practice.
  • Each torch emits light at the same intensity.
  • Each torch points towards a different area ...