in today's video we're going to look at why objects appear the color they do the first thing to know is that visible light is made up of a whole spectrum of different colors from red which has the longest wavelength but lowest frequency all the way to violet which has the shortest wavelength but the highest frequency and i hope you remember the order of these colors you can use the acronym roy g biff where each letter stands for color white and black aren't on the spectrum though because white light is a combination of all the wavelengths which together make white and blackness is just an absence of light so if there is no light it will appear black now which particular color and object appears depends on two things the wavelengths of light that are hitting it and the properties of that particular object together these will determine which light rays are absorbed reflected or transmitted and so determine how the object appears opaque objects are those that don't transmit any light like a cat this means that all the wavelengths of light are either absorbed or reflected and it's the reflected ones that determine the color so this gas appears blue because it's reflecting the blue wavelengths of light and absorbing all of the others in some cases though an object might reflect a range of wavelengths that together combine to give a particular color for example this piece of cheese might appear yellow because it's reflecting yellow wavelengths or because it's reflecting both red and green wavelengths which combine to make yellow transparent and translucent objects on the other hand transmit lots of the light that hits them which means that it passes straight through for transparent objects like the glass in windows they're almost completely see-through because they transmit nearly all of the light with only a small fraction being absorbed or reflected meanwhile translucent objects only transmit some of the light and the proportion of light they transmit determines how well we can see through them the color of a translucent object like a plastic bottle is normally determined by which wavelengths are transmitted most for example this bottle appears green because the green wavelengths are being transmitted most whereas the other wavelengths are being absorbed and so aren't reaching our eye like the green wavelengths are the last thing we need to look at are color filters which are used to filter out particular colors so that only certain wavelengths can pass through they work by only transmitting certain wavelengths of light while absorbing the rest a primary colour filter is one that only allows one of the three primary colours to be transmitted so red green or blue for example if we put white light which remember contains all the different wavelengths of light through a green filter then only the green wavelength would get through so if we looked at white paper through the filter then it would appear green because only the reflected green waves would make it through whereas if we looked at a blue object which must be reflecting only blue light through a green filter then it would appear black because the filter would block the blue light from passing through and so no light would be reflected into your eye filters that aren't for primary colors like yellow or indigo filters let through both the wavelengths of light that are the same color as the filter and also wavelengths of the primary colors that can be added together to make that color for example yellow filters will let through yellow light but also let through red and green because red and green combine to make yellow meanwhile indigo filters will let through indigo wavelengths but also let through blue and red as blue and red light combine to make indigo anyway that's everything for this video today so hope that all made sense and we'll see you again soon you