InterviewSolution
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InterviewSolution
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Notes for human eye |
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Answer» Thank to all 1. The Human Eye It is a natural optical instrument\xa0which is used to see the objects by human\xa0beings. It is like a camera which has lens and\xa0screen system.(i) Retina :\xa0It is a light sensitive screen inside\xa0the eye on which image is formed. It contains\xa0rods and cones.(ii) Cornea :\xa0It is a thin membrane which covers\xa0the eye ball. It acts like a lens which refracts the\xa0light entering the eye.(iii) Aqueous humour :\xa0It is fluid which fills the\xa0space between cornea and eye lens.(iv) Eye lens :\xa0It is a Convex lens made of\xa0transparent and flexible jelly like material. Its\xa0curvature can be adjusted with the help of ciliary\xa0muscles.(v) Pupil :\xa0It is a hole in the middle of iris\xa0through which light enters the eye. It appears\xa0black because light falling on it goes into the\xa0eye and does not come back.(vi) Ciliary muscles :\xa0These are the muscles\xa0which are attached to eye lens and can modify\xa0the shape of eye lens which leads to the\xa0variation in focal lengths.(vii) Iris :\xa0It controls the amount of light entering\xa0the eye by changing the size of pupil.(viii) Optical nerve :\xa0These are the nerves which\xa0take the image to the brain in the form of electrical\xa0signals.2. Accomodation power :\xa0The ability of eye to\xa0change the focal length of eye lens with the\xa0help of ciliary muscles to get the clear view of\xa0nearby objects (about 25 cm) and far distant\xa0objects (at infinity).3. Colour blindness :\xa0Some people do not possess\xa0some cone cells that respond to certain specific\xa0colours due to genetic disorder.4. Myopia (Short sightedness) :\xa0It is a kind of\xa0defect in human eye due to which a person can\xa0see near objects clearly but he can not see the\xa0distant objects clearly.\xa0Myopia is due to(i) excessive curvature of cornea.(ii) elongation of eye ball. Either, if you want so it is given in this app May be this chapter is removed from the syllabus |
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