About diagrams at lightcolourvision.org
Diagrams play a significant role in creating mental representations of knowledge domains. They are widely used in various fields, including science, engineering, and mathematics.
- A mental representation is the way we store and process information in our minds. It’s like a mental model or image of a concept, idea, or object.
- Diagrams are visual representations of information using elements like shapes, lines, symbols, and text.
- Diagrams significantly improve learning outcomes. According to Mayer and Moreno (2002), diagrams can help learners construct mental models of complex information, which can improve their understanding and retention of the material. In addition, diagrams can also support problem-solving tasks by providing visual representations of concepts and relationships between them.
- Diagrams also also believed to provide benefits in terms of visual and spatial reasoning. Visual diagrams, such as charts and graphs, can help learners recognize patterns and relationships, making it easier to interpret and analyze information.
- Diagrams can be used to simplify complex information, making it easier for learners to grasp and retain the material. This is particularly useful where complex processes and systems need to be represented clearly and concisely.
Some types of diagrams used at lightcolourvision.org
- Wave diagrams: Wave diagrams are commonly used to represent light as waves in the study of optics. One of the most common types of diagrams used to represent light waves is the wave diagram, which shows the amplitude and wavelength of the light wave over time. These diagrams can be used to represent the behaviour of light waves in different mediums, such as reflection, refraction, and interference.
- Reflection diagrams: Reflection diagrams show how light waves are reflected off of surfaces, such as mirrors or polished metal. The angle of incidence and the angle of reflection are represented using lines and arrows, allowing learners to visualize the behaviour of light waves as they interact with different surfaces.
- Refraction diagrams: Refraction diagrams show how light waves are bent as they pass through different mediums, such as air, water, or glass. These diagrams use angles and lines to represent the change in direction and speed of light waves as they pass through different mediums.
- Interference diagrams: Interference diagrams show how light waves interfere with each other when they meet at different angles. These diagrams can be used to demonstrate the principles of constructive interference, where waves combine to create a larger amplitude or destructive interference, where waves cancel each other out.
- Polarization diagrams: The measured polarization diagrams are used to represent light as waves and show the orientation of light waves as they vibrate in different directions.
Cognitive Processes in diagrammatic reasoning
- Cognitive processes involved in diagrammatic reasoning refer to the mental activities required to understand and use diagrams effectively. These processes include perception, interpretation, and inference.
- Perception refers to the ability to recognize and understand the visual features of a diagram, such as lines, shapes, and colours.
- Interpretation involves understanding the meaning of the visual features and how they relate to the concepts being represented.
- Inference involves using the information presented in the diagram to draw conclusions and make predictions.
- In addition, diagrammatic reasoning may also involve other cognitive processes such as attention, memory, and problem-solving.
- Attention is required to focus on the relevant features of the diagram and filter out irrelevant information.
- Memory is required to retain the information presented in the diagram and apply it to new situations.
- Problem-solving is required to use the information presented in the diagram to solve problems and make decisions.
Diffraction of electromagnetic radiation, including visible light, refers to various phenomena that occur when an electromagnetic wave encounters an obstacle or passes through an opening.
- Diffraction and interference are phenomena associated with all kinds of waves. Electromagnetic waves are a special case however because of their unique behaviour.
- Diffraction of electromagnetic waves deals with the way light bends around the edges of obstacles into regions that would otherwise be in shadow.
- Interference deals with the way that electromagnetic waves behave during the diffraction process.
- Diffraction can be produced by the edges or by a hole (aperture) in any opaque surface or object.
- Diffraction causes a propagating electromagnetic wave to produce a distinctive pattern as waves interfere with one another. The resulting pattern becomes visible if diffracted light subsequently strikes a surface.
Diffuse reflections occur when light scatters off rough or irregular surfaces.
- When microscopic features on a surface are significantly larger than the individual wavelengths of light within the visible spectrum, each wavelength of light encounters bumps and ridges exceeding their size.
- Instead of reflecting neatly in one direction, the light scatters in different directions.
- In this case, scattering doesn’t happen completely randomly. The surface features influence the direction of the scattered light, depending on the angle of incidence and the specific bumps and ridges it encounters.
- This scattering creates diffuse reflections, responsible for the soft, uniform illumination seen on textured surfaces like matte paint or unpolished wood.
- In the case of a matte phone screen, for example, the light doesn’t form a clear reflection of your face but rather creates a soft, hazy glow due to the scattered light.
In the field of optics, diffusion refers to situations that cause parallel rays of light to spread out more widely. When light undergoes diffusion it becomes less concentrated. Diffuse reflections occur when light scatters off rough or irregular surfaces.
- When microscopic features on a surface are significantly larger than the individual wavelengths of light within the visible spectrum, each wavelength of light encounters bumps and ridges exceeding their size.
- Instead of reflecting neatly in one direction, the light scatters in different directions.
- In this case, scattering doesn’t happen completely randomly. The surface features influence the direction of the scattered light, depending on the angle of incidence and the specific bumps and ridges it encounters.
- This scattering creates diffuse reflections, responsible for the soft, uniform illumination seen on textured surfaces like matte paint or unpolished wood.
- In the case of a matte phone screen, for example, the light doesn’t form a clear reflection of your face but rather creates a soft, hazy glow due to the diffused light.
Digital printing uses the CMYK colour model to enable cyan, magenta, yellow and black inks to be used to output digital files onto paper and other sheet materials.
- Digital printers typically overlay highly reflective white paper with cyan, magenta, yellow and black inks or toner.
- CMYK is a subtractive colour model suited to working with semi-transparent inks.
- Printing has a smaller gamut than TV, computer and phone screens which rely on light emission, rather than reflection of light off sheets of paper.
- Digital screens produce comparatively brighter colours than printers because the amplitude of each wavelength of light is larger than can be achieved by a printer.
- Digital printers produce dull and less intense colours than digital screens because the amplitude of each wavelength of light is smaller when light is reflected off paper through inks.
A digital screen (or digital display) is an output device for the presentation visual of information. RGB digital screens are used in TVs, computers, phones and projectors.
- Digital screens use the RGB (red, green, blue) colour model to represent and display information.
- The range of colours that different types of screens can display depends on their technology and specifications.
- Many RGB digital screens include light-emitting diodes (LEDs) that can directly or indirectly adjust the intensity of red, green and blue light within each addressable component of the screen to produce pixels of colour that together produce an image.
- LEDs are typically used to backlight LCD (liquid crystal display )screens. Different colours are created by colour filters and by adjusting the amount and the polarization of light that is allowed to pass through the crystal sub-pixels that make up each pixel on the screen.
- In an OLED display, each pixel provides its own illumination. The organic materials in the OLED emit light when an electric current is applied. Because each pixel can be turned on or off individually, OLED displays can achieve deeper blacks (by completely turning off pixels) and a higher contrast ratio compared to LED-backlit LCD screens.
Rainbows can be modelled as six concentric two-dimensional discs as seen from the point of view of an observer. Each disc has a different radius and contains a narrow spread of colours. The red disc has the largest radius and violet the smallest.
- The colour of each disc is strongest and most visible near its outer edge because this is the area into which light is most concentrated from the point of view of an observer.
- This concentration of light near the outer edge of each disc results from the path of rainbow rays.
- The term rainbow ray describes the path that produces the most intense experience of colour for any particular wavelength of light passing through a raindrop.
- The intensity of the colour of each disc reduces rapidly away from the rainbow angle because other rays passing through each raindrop diverge from one another and so are much less concentrated.
- The divergence of rays of light after exiting a raindrop is often called scattering.
- From the point of view of an observer, the six discs are superimposed upon one another and appear to be in the near to middle distance in the opposite direction to the Sun.
- There is no property belonging to electromagnetic radiation that causes a rainbow to appear as bands or discs of colour to an observer. The fact that we do see distinct bands of colour in the arc of a rainbow is often described as an artefact of human colour vision.
- To model rainbows as discs allows us to think of them as forming on flat 2D curtains of rain.
- Rainbows are often modelled as discs for the same reason the Sun and Moon are represented as flat discs – because when we look into the sky, there are no visual cues about their three-dimensional form.
- Each member of the set of discs has a different radius due to the spread of wavelengths of light it contains. This can be explained by the fact that the angle of refraction of rays of light as they enter and exit a droplet is determined by wavelength. As a result, the radius of the red disc is the largest because wavelengths corresponding with red are refracted at a larger angle (42.40) than violet (40.70).
- From the point of view of an observer, refraction stops abruptly at 42.40 and results in a sharp boundary between the red band and the sky outside a primary rainbow.
- The idea of rainbows being composed of discs of colour fits well with the fact that there is a relatively clear outer limit to any observed band of colour.
In the field of optics, dispersion is shorthand for chromatic dispersion which refers to the way that light, under certain conditions, separates into its component wavelengths, enabling the colours corresponding with each wavelength to become visible to a human observer.
- Chromatic dispersion refers to the dispersion of light according to its wavelength or colour.
- Chromatic dispersion is the result of the relationship between wavelength and refractive index.
- When light travels from one medium (such as air) to another (such as glass or water) each wavelength is refracted differently, causing the separation of white light into its constituent colours.
- When light undergoes refraction each wavelength changes direction by a different amount. In the case of white light, the separate wavelengths fan out into distinct bands of colour with red on one side and violet on the other.
- Familiar examples of chromatic dispersion are when white light strikes a prism or raindrops and a rainbow of colours becomes visible to an observer.
Distance to a rainbow
Rainbows are formed from the millions of individual raindrops that happen to be in exactly the right place at the right time, so it is difficult to be precise about how far away a rainbow is.
- Because a rainbow is a trick of the light rather than a solid material object set in the landscape it has no fixed position and is at no fixed distance from an observer. Instead, rainbows move as the Sun and the observer move or as curtains of rain cross the landscape.
- Because a rainbow is composed of light reflecting off and refracting in millions of individual raindrops it might be fair to say that the distance to a rainbow is the distance to the location of the greatest concentration of raindrops diverting photons towards an observer.
- An observer cannot easily estimate the distance to a raindrop or a curtain of rain along their line of sight but the position of clouds or objects in the landscape can help to determine where rain is falling.
- The position of a rainbow is primarily determined by angles. The angles are constants and result from the physical properties of light and water droplets, not least the laws of reflection and refraction.
- As an observer moves, the rainbow they see moves with them and the angles are preserved.
Size of a rainbow
- Just as the visual impression of the size of the moon depends on how near it is to the horizon, the apparent diameter of a rainbow is also affected by other features in the landscape.
Duration of a rainbow
- A rainbow may be visible for minutes on end before receding slowly into the distance. In other situations, a rainbow may appear one moment and be gone the next.
