Incident – Light, Colour, Vision

Send us your feedback

Your name and email address will be used solely to provide you with information you have specifically requested. See our privacy policy at https://lightcolourvision.org/privacy/.

We welcome your feedback 🙂

Did you find what you were looking for on lightcolourvision.org?
Did you find an error or typo?
Would you like to contact us?
Would you like to collaborate in some way (partner organisation or individual)?

Become a lightcolourvision.org citizen!!

Your name and email address will be used solely to provide you with information you have specifically requested. See our privacy policy at https://lightcolourvision.org/privacy/.

Get involved! Join us in one of the following citizenship roles. We very much look forward to hearing from you.

Patron: A patron is someone who wants to attach their name to lightcolourvision.org because they share our values and beleive in what we are doing. We invite you to become a patron because you want to stand by us, to be counted and to add your weight to our foundations. You don’t need to be well known, have a public profile or have time to spare. To become a patron is simply to say . . .count me in.
Sponsor: Sponsors of lightcolourvision.org are individuals, organisations or businesses who want to provide practical support to our efforts. You can sponsor us by making some kind of regular pledge of support or by helping us to realise a specific aim or aspiration.
Contributing editor: Our contributing editors are members of the team and may be involved in developing and editing content for the site. Some of our contributing editors have a particular knowledge of subjects we cover, others are programmers or interested in developing the design or functionality of the site.
Collaborator (partner organisation and individuals): Collaborators and partners have similar aims or objectives as lightcolourvision.org. We work with them to promote common causes.

We would love to hear how you would like to get involved with us all at lightcolourvision. Or just get in touch and we can explain more 🙂

Would you like to contact us?

Your name and email address will be used solely to provide you with information you have specifically requested. See our privacy policy at https://lightcolourvision.org/privacy/.

[contact-form-7 404 "Not Found"]

Would you like to subscribe to our Newsletter?

What is a pledge?

A pledge is an amount that a supporter offers to contribute if the crowdfunding campaign is successful.

If the campaign doesn’t reach its funding goal, then supporters will not be asked to settle their pledges.

If the crowd-funding campaign is a success, then supporters will receive an email offering various ways to transfer the pledged amount.

Two further attempts will be made to collect pledged amounts.

If these efforts are unsuccessful the pledge will be recorded as unpaid, but the amount pledged will be counted towards the success of the campaign.

How to use the Colour Finders

Use a desktop or laptop computer to view these Colour Finders
Select the Colour Finder you want to explore
The Colour Finder will open in the Image Library
Select the Finder again to open it as a PDF in your Browser
Select FULL-SCREEN MODE in your Browser
Use arrow keys [< or >] to move from page to page

Answer

A subtractive colour model subtracts colours from white light! Subtractive colour models are used for mixing paints, pigments, inks and dyes! As these products are mixed together and applied to a surface they subtract from the amount of light they reflect, eventually reducing the colour seen by an observer to black.

Answer

Orange, green and purple are the RYB secondary colours!

Answer

Red, yellow and blue primary colours produce a dark brown when mixed together because each colour subtracts from the wavelengths of light reflected towards an observer!

Answer

Both are subtractive colour models. Subtractive colour models such as CMY or RYB are used for mixing paints, pigments, inks and dyes!

Answer

Red, yellow and blue are the three primary colours used with the RYB colour model.

Answer

The RYB colour model is a subtractive colour model widely used for mixing artists paints and introducing colour to children. It is well suited to powder, acrylic and oil paints.

Answer

Magenta is a primary colour in the CMY colour model!

Answer

The frequency of incident light is unchanged as it travels from air into glass so its colour remains the same!

Answer

The wavelength of incident light decreases as it travels from air into glass!

Answer

Yes! Every wavelength of light is affected to a different degree by the refractive index of a material and as a result, changes direction by a different amount when passing from one medium to another!

Answer

Yes! Light travels faster in air than in glass!

Answer

The angles of incidence and reflection are measured between the rays and the normal!

Answer

Yes! The angle of incidence of a ray of light as it strikes a surface is always the same as the angle of reflection!

Answer

Yes! As light crosses the boundary from one medium to another through which it travels more slowly, then it will bend towards the normal!

Answer

Every wavelength of light is affected to a different degree by the refractive index of a material and as a result changes direction by a different amount when passing from one medium (such as air) to another (such as glass)!

Answer

Chromatic dispersion refers to the way that light separates into its component wavelengths (and so colours), under certain conditions!

Answer

The angle of refraction as light crosses their boundary!

Answer

In mathematics, the sine of an angle within a triangle is produced by calculating the ratio of the length of the side that is opposite that angle to the length of the longest side of the triangle (the hypotenuse).

Answer

Snell’s law is the other term used for the law of refraction!

Answer

Index of refraction is the other term used for refractive index!

Answer

When light crosses a boundary into a medium with a high refractive index (eg. diamond = 2.42) there is a significant change in direction.

When light crosses a boundary into a medium with a low refractive index (eg. water = 1.333) there is a less significant change in direction.

Answer

The refractive index of a medium is calculated by dividing the speed of light in a vacuum by the speed of light in another medium! In this case, the speed of light in a vacuum is being divided by the speed of light in a vacuum so the answer = 1!

Answer

The refractive index of a medium is calculated by dividing the speed of light in a vacuum by the speed of light in another medium!

Answer

Refractive index (index of refraction) is a measure of how much slower light travels through a given medium than through a vacuum.

Answer

Snell’s law deals with changes in the angle of incidence and angle of refraction as light travels through different media!

Answer

As light travels from a fast medium such as air to a slow medium such as water it bends toward ‘the normal’ and slows down. As light passes from a slow medium such as diamond to a faster medium such as glass it bends away from ‘the normal’ and speeds up.

Answer

‘The normal’ is an imaginary line drawn on a ray diagram perpendicular to, so at a right angle to (90⁰), to the boundary between two media!

Answer

A medium is any transparent material through which an electromagnetic wave propagates (plural media)!

Answer

Refraction refers to the way light changes speed and direction as it travels across the interface between one transparent medium to another!

Answer

Reflection takes place when incoming light strikes the surface of a medium, some wavelengths are obstructed, and the wavefront bounces off and returns into the medium from which it originated!

Answer

Incident light refers to incoming light that is travelling towards an object or medium!

Answer

In a ray diagram, a light ray is a way of tracing the motion of light, including its direction of travel, and what happens when it encounters different media!

Answer

300,000 kilometres per second!

Answer

Yes! The speed of light depends on the optical density of a medium!

Answer

Frequency of an electromagnetic wave in a vaccuum is calculated by dividing the speed of light by the wavelength of the wave!

Answer

The frequency of an electromagnetic wave is a measurement of the number of wave oscillations passing a given point in a given period of time!

Answer

The wavelength of an electromagnetic wave is a measurement of the length of a single oscillation of the wave!

Answer

Yes! Every colour in a colourwheel can be produced my mixing different proportions of red, green and blue primary colours!

Answer

Yes! Equal proportions of primary colours are used to produce secondary colours!

Answer

Cyan, magenta and yellow are the three secondary colours when building an RGB colourwheel!

Answer

Red, green and blue are the three primary colours used when building an RGB colourwheel!

Answer

Yes! Every colour on a colour wheel is produced by mixing equal proportions of the colours on either side!

Answer

No! Because of the way colour wheels divide up when using decimal or hexadecimal notation, the intermediary colours between secondaries do not always include tertiary colours. Tertiary colours are produced by using equal proportions of secondary colours!

Answer

Yes! There are always secondary colours between primary colours!

Answer

Yes! All RGB colour wheels start with the three primary colours: red green and blue!

Answer

There are twelve tertiary colours in an RGB colour wheel with eighteen colours!

Answer

There are six secondary colours in an RGB colour wheel with six colours!

Answer

There are three primary colours in an RGB colour wheel!

Answer

Overlapping wavelengths of light corresponding with cyan, magenta and yellow make white because, when reflected off a neutral coloured surface, each adds more wavelengths to the reflected light!

Answer

Inks corresponding with the three CMY primary colours produce black during printing because each colour subtracts from the wavelengths of light reflected off the paper towards an observer!

Answer

When wavelengths corresponding with red, green and blue are projected onto a neutral coloured surface in equal proportions they produce white!

Answer

No! There is no single wavelength in the visible spectrum that corresponds with magenta!

Answer

Blue and red are the two primary RGB colours that together make magenta!

Answer

Cyan is a primary colour in the CMY colour model!

Answer

A printer that uses CMYK inks adds black (K) ink to cyan, magenta and yellow to produce deeper blacks!

Answer

Magenta is a secondary colour in the RGB colour model!

Answer

Yes! Cyan is a spectral colour with a wavelength of around 510 nanometres (nm)!

Answer

In the RGB colour model green and blue are the two primary colours that together make cyan!

Answer

Cyan is a secondary colour in the RGB colour model!

Answer

Because a colour wheel demonstrates the effect of mixing different proportions of the three RGB primary colours – red, green and blue!

Answer

A computer screen uses the RGB colour model. Each pixel contains three tiny semiconductors that produce red, green and blue light! The colour we see changes as the intensity of light produced by each semiconductor increases or decreases!

Answer

When spectral colours are arranged in a diagram, the order in which they appear corresponds with their wavelength and so their place in the visible part of the electromagnetic spectrum.

Answer

Red and green are the two primary colours of light that together make yellow?

Answer

Spectral colours are the colours produced by different wavelengths of light. Sunlight and rainbows are composed of spectral colours. RGB colour is an additive colour model in which red, green and blue light is combined in various proportions to produce the appearance of other colours.

Answer

An RGB colour wheel is a way of exploring the relationship between red, green and blue primary colours when they are mixed to produce secondary and tertiary colours etc!

Answer

There are 6 tertiary colours in the RGB colour model! They result from mixing a primary and secondary colour. So a tertiary colour is produced by mixing red-yellow or green-cyan etc!

Answer

Red, green and blue are the three primary colours in the RGB colour model!

Answer

When wavelengths corresponding with red, green and blue are projected onto a neutral coloured surface they produce white!

Answer

A subtractive colour model subtracts colours from white light! Subtractive colour models such as CMY or RYB are used for mixing paints, pigments and dyes! As these products are mixed together and applied to a surface they subtract from the amount of reflected light, eventually reducing the colour seen by an observer to black.

Answer

Cyan, magenta and yellow are the three primary colours used for digital printing. They are subtractive primaries, so mixed together they produce black!

Answer

When red (660 nm), green (525 nm) and blue (460 nm) colours of light are projected at the same intensity onto a neutral coloured surface they produce white!

Answer

No! Human vision relies on trichromacy which is not the same as the RGB colour system. But when red, green and blue light is mixed together in different proportions the human eye sees all the colours of the visible spectrum!

Answer

Cone cells are the light sensitive neurons in the retina at the back of our eyeballs!

Answer

Yes! Spectral colours can be combined together to produce orange, yellow and violet in the correct proportions!

Answer

Yes! ROYGBV are all spectral colours and so can be produced by a single wavelength of light!

Answer

Yes! ROYGBV are all spectral colours and so each can be produced by a single wavelength of light between 480 and 700 nanometres!

Answer

Secondary colours are the colours produced by mixing pairs of primary colours in equal proportions. The RGB secondary colours are cyan, magenta and yellow!

Answer

RGB is a colour model used to produce a full palette of colours by mixing red, green and blue light sources in different proportions!

Answer

No! The colours produced by mixing RGB primary colours are not spectral colours because they are not produced by a single wavelength of light!

Answer

Yes! Each colour in a rainbow between red and violet is a spectral colour!

Answer

A typical human eye will respond to wavelengths between 390 to 700 nanometers!

Answer

Spectral colours are all the colours between red and violet that can be produced by a single wavelength of light. Sunlight is composed of spectral colours!

Answer

Additive primary colours are three wavelengths of light that produce white when combined together in equal proportions!

Answer

The visible spectrum includes all the wavelengths of light the human eye is sensitive to and results in the colours we see between red and violet!

Answer

A non-spectral colour is any colour that can not be produced by a single wavelength of visible light!

Answer

Yes! Every spectral colour corresponds with a single wavelength of visible light!

Answer

Red, green and blue are the three additive primary colours used in the RGB colour model!

Answer

Additive primary colours are three wavelengths of light that produce white when combined together in equal proportions!

Answer

A continuous spectrum is produced by an inclusive band of wavelengths of light between any two points on the electromagnetic spectrum.

Answer

White light is the name for light containing all the wavelengths of the visible spectrum!

Answer

The visible spectrum is the small part of the electromagnetic spectrum our eyes are tuned to!

Answer

ROYGBV refers to red, orange, yellow, green, blue and violet. ROYGBV are the spectral colours accociated with rainbows and the diffusion of white light!

Answer

RGB refers to the colours red, green and blue. These are the primary colours used by the RGB colour model to mix wavelengths of light to produce a palette of as many as 16 million colours!

Answer

Millimetres, centimetres, metres and kilometres are all used to measure the wavelengths of radio waves!

Answer

Yes! The wavelength and speed of light a ray of light change as they travel through different media.

Answer

No! The colour of a ray of light remains the same because frequency doesn’t change as light travels through different media.

Answer

No! Both crown glass and diamonds are slow media because they significantly reduce the speed of light?

Answer

The maximum speed of light occurs in a vacuum! Light travels in air at 99% of the speed of light in a vacuum!

Answer

Yes! The speed of light is affected by the medium through which it propagates!

Answer

Lower frequency = Longer wavelengths!

Answer

Shorter wavelengths = Higher frequency!

Answer

Gamma rays transport more energy than any other form of electromagnetic radiation!

Answer

Gamma rays have a higher frequency than any type of electromagnetic radiation!

Answer

The unit used to measure the frequency of light is the hertz. But the frequency of visible light corresponds to a band of frequencies in the vicinity of 430–770 terahertz (THz)! There are a trillion (1,000,000,000,000) terahertz in a hertz!

Answer

Yes! As the frequency of oscillations of an electromagnetic wave increase the wavelength decreases!

Answer

Yes! Energy increases with frequency!

Answer

Violet has the highest frequency of visible light!

Answer

There are 1000 Kilohertz in one Hertz!

Answer

The hertz is used to measure the frequency of electromagnetic waves! But because the frequency of electromagnetic waves vary enormously, different prefixes are used to aid measurement. Here are four examples: Kilohertz, megahertz, gigahertz and terahertz!

Answer

There are trillion (1,000,000,000,000) picometres in a metre!

Answer

Yes! Gamma rays have the shortest wavelengths within the electromagnetic spectrum!

Answer

The largest unit used to measure the wavelength of electromagnetic waves is the kilometre!

Answer

Gamma rays have a shorter wavelength than radio waves!

Answer

Infrared and ultraviolet are froms of electromagnetic radiation with wavelengths just outside the visible spectrum!

Answer

The unit used to measure the wavelengths of visible light is the nanometre!

Answer

The unit used to measure wavelength is the metre. Because the size of electromagnetic waves vary, different prefixes are used to aid measurement. Here are six examples: kilometre, centimetre, millimetre, micrometre, nanometre and picometre!

Answer

In the case of light waves, to propagate means to travels through a medium in a particular direction!

Answer

The angle between the electric and magnetic field is 90⁰!

Answer

An electromagnetic wave is the result of the interaction of electric and magnetic fields!

Answer

Yes! A wave with lower frequency has a longer wavelength!

Answer

Yes! Waves with lower frequencies have longer wavelengths!

Answer

Gamma rays transport more energy than any other band of wavelengths within the electromagnetic spectrum!

Answer

Gamma rays have the shortest wavelengths of any type of radiation within the electromagnetic spectrum!

Answer

The unit used to measure wavelength is the metre. Because the size of electromagnetic waves vary, different prefixes are used to aid measurement. Here are six examples: kilometre, centimetre, millimetre, micrometre, nanometre and picometre!

Answer

The range of wavelengths that correspond with green is between 570 – 495 nanometres!

Answer

Red has the longest wavelength whilst violet has the shortest!

Answer

Yes! Wavelength is measured in nanometres!

Answer

Yes! The colour of visible light depends on its wavelength.

Answer

Yes! A light wave is another name for an electromagnetic wave! But remember that not all forms of light are visible to the human eye.

Answer

The unit of measurement for wavelengths of visible light is the nanometre (nm)!

Answer

Yes! Each wavelength of light corresponds with a different colour seen by an observer!

Answer

The invisible band of wavelengths next to red is the infrared?

Answer

Rainbows produce spectral colours as sunlight is refracted by raindrops!

Answer

nm is shorthand for nanometre!

Answer

Violet is the band of colour with the shortest wavelength!

Answer

Red is the band of colour with the longest wavelength!

Answer

Red, orange, yellow, green, blue and violet are the bands of colour we see in a rainbow!

Answer

Yes! Visible light is a form of electromagnetic radiation!

Answer

Wavelengths visible to the eye are in a band between approximately 390 to 700 nanometres!

Answer

Because different wavelengths of light are reflected off the surface of objects. Every surface has unique properties!

Answer

No! The visible spectrum is just the small part of the electromagnetic spectrum our eyes are tuned to!

Answer

No! Light only becomes visible when it strikes a medium or object!

Answer

Yes! The energy that the sun emits is called electromagnetic radiation!

Answer

Too much ultra-violet radiation causes sunburn!

Answer

All forms of light travel at 299,792 kilometres per second in a vacuum (almost 300,000 km/sec)!

Answer

Sunlight can be described in terms of both waves and particles!

Answer

Other names for sunlight include daylight, sunshine, visible light, light and electromagnetic radiation!

Answer

Sunshine is important to human beings because without light we can’t see!

Answer

The ball is painted cyan! (Now check out the next question).

Answer

When white light stikes an object its colour is determined by which wavelengths of light are absorbed and which wavelengths are reflected towards the observer!

Answer

When wavelengths of light corresponding with red, green and blue are projected at equal intensity onto a dark surface it appears white to an observer!

Answer

White light contains all the wavelengths of the visible spectrum at equal intensity!

Answer

Yes! Because the Sun radiates light at all wavelengths of the electromagnetic spectrum it therefore also emits light at all wavelengths of the visible spectrum!

Answer

The Sun radiates light at all wavelengths of the electromagnetic spectrum!

Answer

Yes! As the frequency of oscillations of an electromagnetic wave increase the wavelength decreases!

Answer

Yes! Energy increases with frequency!

Answer

Hertz. Kilohertz. Megahertz. Gigahertz. Terahertz!

Answer

A light wave in a vacuum travels at 300,000 kilometres (km) per second! Or to be exact, 299,792 km/sec.

Answer

The frequency of a wave is a measurement of the number of waves passing a given point in a given period of time!

Answer

Yes! A wave-cycle can be measured from any point on a wave to the same point on the next wave!

Answer

The lowest point in the oscillation of a wave is called the trough!

Answer

Yes! light waves propagate through a vacuum in a straight line!

Answer

Blue and violet are two of the colours with the shortest wavelengths!

Answer

Red and orange are two of the colours with the longest wavelengths!

Answer

Some estimates of the number of colours the human eye can distinguish between run into the millions!

Answer

Yes! Every wavelength of light corresponds with a different colour!

Answer

Our eyes are tuned to visible light – the visible part of the electromagnetic spectrum!

Answer

Names for solar radiation include solar energy and light!

Answer

The sun emits electromagnetic radiation!

Answer

The sun generates energy as a result of thermonuclear fusion!

Answer

The star at the centre of our solar system is called the Sun!