how does on see different colours at different angles on seals and money?

Answer 1

Because there is a "serrated" surface embedded in the print that defracts the light and scatters it into its different components. The principal is the same as a Prism. Visible light is made of many colors, from blue to red and if you put white light into a prism it will separate it into the many colors of the rainbow. The reason you can see the different colors on the seal is because when you move the bill around, you are looking from different angles and seeing that particular frequency of the light spectrum