# Wavelengths from Red to Violet

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## Description

To find out more about the diagram above . . . . read on!

#### Wavelengths from Red to Violet

Look carefully at the diagram at the top of the page. Now check out the following questions (and answers)!

1. Is visible light a form of electromagnetic radiation?
2. Do different wavelengths of light correspond with different colours?
3. How many different colours can the human eye see in ideal conditions?
4. Name two colours with the longest wavelengths?
5. Name two colours with the shortest wavelengths?

Introducing the diagram! Read back and forward between the image at the top of the page and the explanation below!

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 (a rainbow for example) as six bands of colour, each and every wavelength between 700 and 430 nanometres is a different colour.
• The list on the left shows the range of wavelengths corresponding with each band of colour.
• The red arrow, for example, corresponds with wavelengths between 700 nanometres and 620 nanometres. Red is the colour an observer sees if any wavelength in that range strikes a neutral coloured surface.
• The scale along the bottom is marked in nanometres and shows the visible spectrum divided into coloured bands.

Remember that:

• Objects appear to be different colours to an observer depending on their wavelength.
• The name given to light that contains all wavelengths of the visible spectrum is white light.
• When all wavelengths contained in white light reflect off a neutral coloured surface then the object appears white to an observer.
• When a narrow band of wavelengths reflect off a neutral coloured surface then the object appears coloured to an observer.
• The colour an observer sees depends on the wavelengths of visible light emitted by a light source and on which of those wavelengths are reflected off an object.
• Although a human observer can distinguish between many thousands of wavelengths of light in the visible spectrum our brains often produce the impression of bands of colour.

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

#### Some Key Terms

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

#### Slides

All images on the lightcolourvision.org website are available for download as either slides or diagrams.

All slides share common specifications:

• Titles: All slides have titles.
• Backgrounds: Black, framed with a violet gradient.
• Size: 1686 x 1124 pixels (3:2 aspect ratio).
• Slides are available in two file formats: JPG, AI (Adobe Illustrator).

Slides are optimized for viewing on-screen or with a projector.
Diagrams are optimized for printing on A4 pages in portrait format.

#### Diagrams

All images on the lightcolourvision.org website are available for download as either slides or diagrams.

All diagrams share common specifications:

• Titles: No titles.
• Backgrounds: White.
• Size: 1686 pixels wide. So all diagrams reproduce at the same scale when inserted into Word documents etc.
• Labels: Calibri 24pt Italic.
• Diagrams are available in two file formats: JPG, AI (Adobe Illustrator).

Diagrams are optimized for printing on A4 pages in portrait format.
Slides are optimized for viewing on-screen or using a projector.

#### JPG file format

• Text on JPG images with white backgrounds is styled as Calibri 24pt Italic.
• If the image you need is not exactly right, download it as an AI (Adobe Illustrator) file and edit it.
• All the images on these Resource Pages were created in Adobe Illustrator and are vector drawings.

Did you know:

• JPG stands for Joint Photographic Experts Group who created the standard.
• The JPG file extension is used interchangeably with JPEG.
• JPG files can be compressed for use on websites.
• JPG files can be placed or pasted directly into MS Office documents.