PE - Incident ray$EF$ - Refracted rayFS - Emergent ray$\angle A$ - Angle of the prism$\angle i$-Angle of incidence$\angle r$-Angle of refraction$\angle e$-Angle of emergence$\angle D$ - Angle of deviation (b) The prism will split the incident white light into a band of colours. The various colours seen are Violet, Indigo, Blue, Green, Yellow, Orange and Red.OR(a) (i) If a person suffer from both myopia and hypermetropia, such people often require bifocal lenses.(ii) A common type of bifocal lenses consists of both concave and convex lenses. The upper portion consists of a concave lens. It facilitates distant vision. The lower part is a convex lens. It facilitates near vision.(b) For correcting distant vision;Power, $P=-3 D$Using $P=\frac{1}{f}$ where $f=$ focal length of the lens.$\Rightarrow f=\frac{1}{-3 D}=-0.33\text{ m}$The focal length of the lens for correcting distant vision $=-0.33\text{ m}$.Minus sign of focal length tells us that it is a concave lens.For correcting near visionPower, $P=+3 D$Using $P=\frac{1}{f}$ where $f=$ focal length of the lens.$\Rightarrow f=\frac{1}{3}=+0.33\text{ m}$The focal length of the lens for correcting distant vision $=+0.33\text{ m}$.Plus sign of focal length tells us that it is a convex lens.