About colour brightness & light intensity
- The perception of colour depends on the wavelengths that reach an observer’s eyes. Red has a longer wavelength, while violet has a shorter wavelength.
- Any colour (e.g. red, magenta, or violet) can be defined by its hue, saturation, and brightness.
- Saturated colours are produced by a single wavelength of light or a narrow band of wavelengths.
- The brightness of a colour depends on the intensity of the light emitted by a light source (e.g., a coloured light bulb) and the amount of light reflected from a coloured surface.
- So, for example, the texture of a surface can affect brightness even when the intensity of the light source remains constant.
- The intensity of light, along with factors such as phase and interference, are directly related to the amplitude of an electromagnetic wave.
- Amplitude measures the height of light waves from the centre-line of a waveform to its crest or to a corresponding trough.
- Colour brightness, light intensity, and the amplitude of a light wave can all be thought of in terms of the number of photons that strike the eye of an observer.
- Therefore, increasing the amplitude of a wavelength of light will increase the number of photons falling on an object, making it appear brighter to an observer.