[custom_adv] White light is a mixture of all colours, including those that the human eye can’t see. When we say something has colour, what we actually mean is that light of a particular range of wavelengths is reflected more strongly than the light of other wavelengths. [custom_adv] How matter behaves in the presence of light, consequently appearing coloured to us humans, depends on a couple of major factors. [custom_adv] First of all — everything is made up of electrons and atoms, but each substance has a different number of atoms and different electron configuration. [custom_adv] Most objects reflect light, but some are more reflective than others, like metals. This is directly related to the number of free electrons that are able to pass from atom to atom with ease. [custom_adv] Instead of absorbing energy from the light, the free electrons vibrate and the light energy is sent out of the material at the same frequency as the original light coming in. [custom_adv] The human eye and brain translate light into colour. Light receptors within the eye transmit messages to the brain, producing the familiar sensation of colour. [custom_adv] The retina is covered by millions of light-sensitive cells, some shaped like rods and some like cones, and it’s these receptors that process the light and then send this information to the visual cortex. [custom_adv] Rods are mostly concentrated around the edge of the retina and transmit mostly black and white information. Cones transmit the higher levels of light intensity that create the sensation of color and visual sharpness. [custom_adv] These cells, working in combination with connecting nerve cells, give the brain enough information to interpret and name colours. [custom_adv] Think of atoms like bricks in a wall (chemical compound). Imagine throwing a ball into the wall. If the wall is smooth or has sharp corners, the ball may jump back in different directions.
