What would happen when we discard blue and red colours from a Newtons Disk. Will they still for

white Colour? 

 

If the Newton's disc has all the seven colours painted on it, and if red and blue colours are removed, then white light will still be visible.

This is because, other colours like orange (red + yellow) and purple (red + blue) are still present. So, technically all three colours red, green and blue are present.

They will combine and form white colour.

 

If however, the disc has only three primary colours red, green and blue and if we discard two of them then it will not form white colour.