When white light is dispersed through a prism it splits into all the colours of the spectrum, showing that white light is actually made up of all the different colours (a similar thing happens when rainbows are formed) The primary colour in light are Red,BlueandGreen
Red,blue andgreenmixed producewhite Light Blue and redmixed producemagenta Blue andgreenmixed producecyan Redandgreenmixed produceyellow Cyan ,magenta and yelloware secondary colours
Blue light light reflects form blue objects, the others are absorbed
Colour filters work in a similar way
In a red filter only red light passes through the other colours ate absorbed
Only green light passes through a green filter, the others are absorbed
Greenand blue light passes through a cyan filter,the others are absorbed