[ul] [li]Reflection occurs when a wave 'bounces' off a surface[/li] [li]We see things because light is reflected in to our eyes[/li] [/ul] As shown in the example below, where the orange ball is the light source: [img src='https://res.cloudinary.com/deylrqt2d/image/upload/v1487945353/how_you_see_wg6lab.svg' style='width:100vw'] To perceive objects, we have 3 types of cells in our eyes to see colour, these are called [b]Cone Cells[/b]. The three types are: [b]Red[/b], [b]Green[/b] and [b]Blue[/b]. When the light has enough intensity, we can see in colour. However in very dark environments, and night, these cells deactivate. Instead [b]Rod Cells[/b], which are located towards the back of your eyes, are activated, and are activated after about 20 minutes in the dark. These Rod Cells only perceive shades of grey. The cone cells are found in a part of the eye called the [b]Fovea[/b], no Rod cells are there. Rod Cells are found in great concentration on the outer rim of the [b]Retina[/b].