Geometric optics treats light as a collection of rays that travel in straight lines and bend when they pass through or reflect from surfaces.
The aim of a ray diagram is to demonstrate optical phenomena such as absorption, dispersion, polarization, reflection, refraction, scattering and transmission.
https://en.wikipedia.org/wiki/Ray_tracing_(physics)
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!
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!
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!
White light contains all the wavelengths of the visible spectrum at equal intensity!
The Sun radiates light at all wavelengths of the electromagnetic spectrum!
Yes! The wavelength and speed of light a ray of light change as they travel through different media.
No! The colour of a ray of light remains the same because frequency doesn’t change as light travels through different media.
No! Both crown glass and diamonds are slow media because they significantly reduce the speed of light?
The maximum speed of light occurs in a vacuum! Light travels in air at 99% of the speed of light in a vacuum!
Yes! The speed of light is affected by the medium through which it propagates!
Gamma rays have the shortest wavelengths of any type of radiation within the electromagnetic spectrum!
Gamma rays have a higher frequency than any type of electromagnetic radiation!
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!
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: Â Kilohertz, megahertz, gigahertz and terahertz!
Yes! As the frequency of oscillations of an electromagnetic wave increase the wavelength decreases!
Yes! Energy increases with frequency!
Yes! Energy increases with frequency!
Violet has the highest frequency of visible light!
There are 1000 Kilohertz in one Hertz!
Yes! Gamma rays have the shortest wavelengths within the electromagnetic spectrum!
Infrared and ultraviolet are froms of electromagnetic radiation with wavelengths just outside the visible spectrum!
The unit used to measure the wavelengths of visible light is the nanometre!
A light wave in a vacuum travels at 300,000 kilometres (km) per second! Or to be exact, 299,792 km/sec.
In the case of light waves, to propagate means to travels through a medium in a particular direction!
Yes! light waves propagate through a vacuum in a straight line!
The frequency of a wave is a measurement of the number of waves passing a given point in a given period of time!
Yes! A wave with lower frequency has a longer wavelength!
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!
Rainbows produce spectral colours as sunlight is refracted by raindrops!
Yes! The colour of visible light depends on its wavelength.
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.
Blue and violet are two of the colours with the shortest wavelengths!
Some estimates of the number of colours the human eye can distinguish between run into the millions!
Yes! Each wavelength of light corresponds with a different colour seen by an observer!
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/.
Join us in one of the following citizenship roles. We very much look forward to hearing from you.
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 🙂
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.
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/.
Magenta is a primary colour in the CMY colour model!
Cyan is a primary colour in the CMY colour model!
Inks and pigments corresponding with the three CMY primary colours produce black because when mixed together they do not reflect any wavelengths of white light!
A printer that uses CMYK inks uses black (K) to produce darker shadows!
Magenta is a secondary colour in the RGB colour model!
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.
Â
The frequency of incident light is unchanged as it travels from air into glass so its colour remains the same!
Â
Â
Â
Â
Â
Â
Â
Â
Â
Snell’s law is the other term used for the law of refraction!
Â
Index of refraction is the other term used for refractive index!
Â
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!
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!
Refractive index (index of refraction) is a measure of how much slower light travels through a given medium than through a vacuum.
Snell’s law deals with changes in the angle of incidence and angle of refraction as light travels through different media!
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.
‘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!
A medium is any transparent material through which an electromagnetic wave propagates (plural media)!
Refraction refers to the way light changes speed and direction as it travels across the interface between one transparent medium to another!
Incident light refers to incoming light that is travelling towards an object or medium!
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!
300,000 kilometres per second!
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!
Yes! The speed of light depends on the optical density of a medium!
Frequency of an electromagnetic wave in a vaccuum is calculated by dividing the speed of light by the wavelength of the wave!
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!
The wavelength of an electromagnetic wave is a measurement of the length of a single oscillation of the wave!
Yes! Every colour in a colourwheel can be produced my mixing different proportions of red, green and blue primary colours!
Cyan, magenta and yellow are the three secondary colours when building an RGB colourwheel!
Yes! Equal proportions of primary colours are used to produce secondary colours!
Red, green and blue are the three primary colours used when building an RGB colourwheel!
Yes! Every colour on a colour wheel is produced by mixing equal proportions of the colours on either side!
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!
Yes! There are always secondary colours between primary colours!
Yes! All RGB colour wheels start with the three primary colours: red green and blue!
There are six secondary colours in an RGB colour wheel with six colours!
There are twelve tertiary colours in an RGB colour wheel with eighteen colours!
There are three primary colours in an RGB colour wheel!
Because they cancel each other out! The area where they all overlap appears black because no wavelengths of light reach the surface!
When wavelengths corresponding with red, green and blue are projected onto a neutral coloured surface in equal proportions they produce white!
No! There is no single wavelength in the visible spectrum that corresponds with magenta!
Blue and red are the two primary colours of light that together make magenta!
White light is the name for light containing all the wavelengths of the visible spectrum!
Cyan, magenta and yellow are the three primary colours used in pigments or inks. They are the subtractive primaries. Mixed together they produce black!
A computer screen uses the RGB colour model. Each pixel contains three tiny semi-conductors, one red, one green and one blue! The colour changes as the intensity of each colour alters!
Yes! Cyan is a spectral colour with a wavelength of around 510 nanometres (nm)!
Cyan is a secondary colour in the RGB colour model!
In the RGB colour model green and blue are the two primary colours of light that together make cyan!
Because a colourwheel demonstrates the effect of mixing different proportions of the three primary colours red, green and blue!
Because spectral colours correspond with the visible part of the electromagnetic spectrum!
Red and green are the two primary colours of light that together make yellow?
Spectral colours are the colours produced by different wavelengths of light. RGBÂ colour is an additive colour model in which red, green and blue are combined in various proportions to produce other colours.
An RGB colourwheel is a way of exploring the relationship between red, green and blue primary colours, secondary and tertiary colours etc!
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!
Red, green and blue are the three primary colours in the RGB colour model!
When wavelengths corresponding with red, green and blue are projected onto a neutral coloured surface they produce white!
When wavelengths corresponding with red, green and blue are projected at the same intensity onto a neutral coloured surface they produce white!
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!
Cone cells are the light sensitive neurons in the retina at the back of our eyeballs!
Yes! Spectral colours can be combined together to produce orange, yellow and violet in the correct proportions!
Yes! ROYGBV are all spectral colours and so can be produced by a single wavelength of light!
Yes! ROYGBV are all spectral colours and so can be produced by a single wavelength of light!
Secondary colours are the colours produced by mixing pairs of primary colours in equal proportions. The RGB secondary colours are cyan, magenta and yellow!
RGB colours are the full range of colours produced by mixing red, green and blue light in different proportions!
No! The colours produced by mixing primary colours are not spectral colours because they are not produced by a single wavelength of light!
Yes! Each colour in a rainbow between red and violet is a spectral colour!
A typical human eye will respond to wavelengths between 390 to 700 nanometers!
Spectral colours are all the colours between red and violet!
The visible spectrum is the small part of the electromagnetic spectrum our eyes are tuned to!
ROYGBV are the initials of red, orange, yellow, green, blue and violet. ROYGBV are the spectral colours accociated with rainbows and the diffusion of white light!
RGB stands for red, green and blue. These are the primary colours used when mixing wavelengths of light to produce additive colours!
Additive primary colours are three wavelengths of light that produce white when combined together in equal proportions!
A continuous spectrum is produced by an inclusive band of wavelengths of light between any two points on the electromagnetic spectrum.
Additive primary colours are three wavelengths of light that produce white when combined together in equal proportions!
Red, green and blue are additive primary colours!
Yes! Every spectral colour corresponds with a single wavelength of visible light!
A non-spectral colour is any colour that can not be produced by a single wavelength of visible light!
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!
Millimetres, centimetres, metres and kilometres are all used to measure the wavelengths of radio waves!
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!
Lower frequency = Longer wavelengths!
Shorter wavelengths = Higher frequency!
Gamma rays transport more energy than any other form of electromagnetic radiation!
Yes! As the frequency of oscillations of an electromagnetic wave increase the wavelength decreases!
There are trillion (1,000,000,000,000) picometres in a metre!
The largest unit used to measure the wavelength of electromagnetic waves is the kilometre!
Gamma rays have a shorter wavelength than radio waves!
The angle between the electric and magnetic field is 900!
An electromagnetic wave is the result of the interaction of electric and magnetic fields!
Gamma rays transport more energy than any other band of wavelengths within the electromagnetic spectrum!
Yes! Waves with lower frequencies have longer wavelengths!
The range of wavelengths that correspond with green is between 570 – 495 nanometres!
Red has the longest wavelength whilst violet has the shortest!
Yes! Wavelength is measured in nanometres!
Wavelengths visible to the eye are in a band between approximately 390 to 700 nanometres!
Sunlight can be described in terms of both waves and particles!
The unit of measurement for wavelengths of visible light is the nanometre (nm)!
The invisible band of wavelengths next to red is the infrared?
nm is shorthand for nanometre!
Violet is the band of colour with the shortest wavelength!
Red is the band of colour with the longest wavelength!
Red, orange, yellow, green, blue and violet are the bands of colour we see in a rainbow!
Yes! Visible light is a form of electromagnetic radiation!
Because different wavelengths of light are reflected off the surface of objects. Every surface has unique properties!
No! The visible spectrum is just the small part of the electromagnetic spectrum our eyes are tuned to!
No! Light only becomes visible when it strikes a medium or object!
Yes! The energy that the sun emits is called electromagnetic radiation!
Too much ultra-violet radiation causes sunburn!
All forms of light travel at 299,792 kilometres per second in a vacuum (almost 300,000 km/sec)!
Other names for sunlight include daylight, sunshine, visible light, light and electromagnetic radiation!
Sunshine is important to human beings because without light we can’t see!
The ball is painted cyan! (Now check out the next question).
Hertz. Kilohertz. Megahertz. Gigahertz. Terahertz!
Yes! A wave-cycle can be measured from any point on a wave to the same point on the next wave!
The lowest point in the oscillation of a wave is called the trough!
Red and orange are two of the colours with the longest wavelengths!
Yes! Every wavelength of light corresponds with a different colour!
Our eyes are tuned to visible light – the visible part of the electromagnetic spectrum!
Names for solar radiation include solar energy and light!
The sun emits electromagnetic radiation!
The sun generates energy as a result of thermonuclear fusion!
The star at the centre of our solar system is called the Sun!