The cheese in your sandwich is orange. The tomato is bright red. The lettuce is green. The light brown bread has a dark brown crust.
We see colours in things because of the way they reflect light. But the colours are really in the light. The light from the sun is a mixture of all colours. We call this type of light white light.
You can see these colours if you shine bright sunlight through a special glass called a prism. When white light goes through a prism, it spreads and separates into a band of colours, like a rainbow. It has six bands of colour – violet, blue, green, yellow, orange, and red.
When white light shines on something, that object absorbs, or soaks up, some of these colours. But it reflects other colours. Objects appear to be the colours they reflect. So the tomato in your sandwich looks red because it reflects red and absorbs other colours. Lettuce reflects green. Black objects absorb nearly all the light that reaches them. So you don’t see any colour in something that is black.
Picture Credit : Google