In the Newton’s Disc Experiment, we learn that white light is the combination of all the colours in the spectrum. We learnt this by colouring a wheel the colours of the rainbow, sticking the paper onto the disc, and spinning the disc as fast as we can, which all the colours would start to blend together and become white. This is due to the persistence of vision, where the human eye can't distinguish details at high speeds, resulting in the additive averaging of colors