1. Myopia Nearsightedness Elongation of eye ball. Use of concave excessive curvature of lens. lens. Longer focal length of 2. Hypermetropia Farsightedness Use of convex eye lens. lens. Shortening of eye ball. 3. Presbyopia Decrease in power of Ageing, leading to weak ciliary Use of eye accommodation muscles and loss of flexibility of glasses having eye lens. bifocal lens. 4. Cataract Milkiness of eye lens Ageing, leading to partial or Surgery. complete loss of eye sight. SOME NATURAL PHENOMENON &CAUSES S.No. Phenomenon Reason 1. Multicolored light coming out of a triangular slab Dispersion of light 2. Rainbow Refraction, dispersion of light and total internal reflection flight in rain drops 3. Twinkling of stars, Advanced sunrise, Delayed Atmospheric refraction of sunlight sunset ,Flattening of disc of sun at sunrise and sunset 4. Blue colour of sky ,Reddening of sun at sun rise Scattering of light and sunset Tyndall effect HUMAN EYE TWINKLING OF STARS FORMATION OF RAINBOWMYOPIA SCATTERING OF LIGHTDISPERSION OF WHITE LIGHT
1. Myopia Nearsightedness Elongation of eye ball. excessive curvature of lens. Use of concave lens. 2. Hypermetropia Farsightedness Longer focal length of eye lens. Shortening of eye ball. Use of convex lens. 3. Presbyopia Decrease in power of accommodation Ageing, leading to weak ciliary muscles and loss of flexibility of eye lens. Use of eye glasses having bifocal lens. 4. Cataract Milkiness of eye lens Ageing, leading to partial or complete loss of eye sight. Surgery. SOME NATURAL PHENOMENON &CAUSES S.No. Phenomenon Reason 1. Multicolored light coming out of a triangular slab Dispersion of light 2. Rainbow Refraction, dispersion of light and total internal reflection flight in rain drops 3. Twinkling of stars, Advanced sunrise, Delayed sunset ,Flattening of disc of sun at sunrise and sunset Atmospheric refraction of sunlight 4. Blue colour of sky ,Reddening of sun at sun rise and sunset Tyndall effect Scattering of light HUMAN EYE TWINKLING OF STARS FORMATION OF RAINBOWMYOPIA SCATTERING OF LIGHTDISPERSION OF WHITE LIGHT
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