A beam of white light is allowed to pass through convex lens parallel to principal axis, the different colours of light converge at different points on the principle axis after refraction. This is called

Step-by-step solution

When a beam of white light passes through a convex lens, it undergoes refraction. The refractive index of the lens material varies for different wavelengths of light, being maximum for violet and minimum for red. Since the focal length of a lens depends on the refractive index according to the lens maker's formula 1 f = ( - 1) ( 1 R₁ - 1 R₂ ) , different colours have different focal lengths. Violet light converges closer to the lens, while red light converges farther away. This inability of a lens to focus all colo