The angle of deviation of light of various colours passing through a triangular prism increases in the order

When a beam of white light passes through a triangular prism, it refracts or bends due to the change in speed of the light as it enters the prism. This causes the different colors of the white light to separate because each color has a slightly different wavelength, and thus a slightly different refractive index. This separation of colors is called dispersion, and it creates a spectrum of colors, from red to violet. The angle of deviation is the angle between the incident ray of white light and the emergent ray of the dispersed colors. This angle is different for different colors because each color is refracted at a slightly different angle. In a triangular prism, the angle of deviation increases with increasing wavelength of light. This means that the color with the longest wavelength, which is red, is refracted the least, while the color with the shortest wavelength, which is blue or violet, is refracted the most. Therefore, the correct option is "red → green → blue", which indicates the order of increasing wavelengths and increasing angles of deviation.