(a) Study the diagram given below and answer the questions that follow: (i) Name the defect of vision depicted in this diagram stating the part of the eye responsible for this condition. (ii) List two causes of this defect. (iii) Name the type of lens used to correct this defect and state its role in this case. OR (b) What is dispersion of white light? State its cause. Draw a diagram to show dispersion of a beam of white light by a glass prism.

(a) (i) The defect of vision depicted in this diagram is myopia or near-sightedness. The part of the eye responsible for this condition is the eye lens. (ii) Two causes of this defect are: (a) Excessive curvature of the eye lens. (b) Elongation of the eyeball. (iii) The type of lens used to correct this defect is a concave lens. Its role in this case is to spread out the light rays before they enter the eye, thereby reducing the focal length and allowing distant objects to be seen clearly. OR (b) Dispersion of white light is the splitting of white light into its component colors when it passes through a prism. This occurs because each color of light has a slightly different wavelength and is refracted at a slightly different angle as it passes through the prism. The cause of dispersion is the difference in refractive indices of the prism material for different wavelengths of light. A diagram to show dispersion of a beam of white light by a glass prism is shown below: