Prisms | The Wonders of Physics | University of Wisconsin–Madison
Because the colors of light travel at different speeds, they get bent by different amounts and come out all spread out instead of mixed up. Violet travels the slowest so it is on the bottom (least bent) and red travels the fastest so is on the top (most bent). The other colors are somewhere in between.
Boom ..... science
Yup @Tripod science says the red ones are the "most bent"