What determines the order of colors in a rainbow - JSS2 Basic science Light Energy II Question

The order of colors in a rainbow, from outermost to innermost, is determined by the wavelengths of light. Red light has the longest wavelength and is on the outer edge of the rainbow, while violet light has the shortest wavelength and is on the inner edge. The order of colors in between follows the sequence of decreasing wavelength: red, orange, yellow, green, blue, indigo, and violet.