How will you prove that light consists of seven colours using Newton's colour disk?
Proof by Newton’s seven color rotating disk method.
Newton drew out a circular disk out of cardboard and painted seven colors of VIBGYOR on its seven sectors. Then he rotated the disk along the axis perpendicular to the disk. When rotating the colors weren’t visible and the disk appeared white. This showed that seven colors when mixed up produces the white light.
You may verify the phenomenon yourself.
- Take a white cardboard cut out a circle like the fig shown above.
- Mark the centre of the circle, draw seven equal sectors each with seven colors of VIBGYOR
- Take a sharp pencil and pass through the middle of the circle and attach the disk on pencil properly
- Rotate the disk by the help of pencil like a top.
- While in rotation you will see the color of the disk is no more there, all that will appear is a white disk.