Beams of red, orange, yellow, green, blue, indigo, and violet, light (ROYGBIV) strike a convex (converging) lens and cross (are brought to a focus). Higher frequency (shorter wavelength) colours, like blue and violet, are refracted more, bringing their focus closer to the lens.. The simulation uses the refractive indices of flint glass, a very heavy material with a high refractive index and high dispersion.