7. Human Eye and Colourful world
1. The least distance of the distinct vision is about ______ cm.
2. The maximum angle, at which we are able to see the whole object is called ___________.
3. The angle of vision for a healthy human being is about .
4. Iris has a small hole in it called __________.
5. The distance between the lens and retina is about _______ cm.
6. The eye-lens forms a _________ and _________ image of an object on the retina.
7. The retina is a delicate membrane, which contains about 125 million receptors called ‘rods’ and ‘cones’ which receive the _____________.
8. In a receptors of eye rods identify the colour and cones-identify the _____________.
9. The maximum focal length of the eye lens is ______ Cm.
10. The minimum focal length of the eye lens is ______ Cm.
11. The ability of eye-lens to change its focal length is called “_______________”.
12. Some people cannot see objects at long distances but can see nearby objects clearly. This type of defect in vision is called ‘__________’.
13. The defect, in which people cannot see objects beyond far point, is called ‘_________’.
14. Myopia is also called _____________.
15. The least distance of distinct vision, the eye lens can form an image on the retina. This distance is called ‘_________’.
16. The point of maximum distance at which the eye lens can form an image on the retina is called ‘_________’.
17. If we can correct myopia then we need to select ____________.
18. Hypermetropia is also known as “___________”.
19. A person with __________ can see distant objects clearly but cannot see objects at near distances.
20. The minimum focal length of eye lens for the person of hypermetropia is greater than __________ cm.
21. The point of minimum distance at which the eye lens can form an image on the retina is called _________(d).
22. To correct the defect of hypermetropia, we need to use a ______________.
23. __________ is vision defect when the ability of accommodation of the eye usually decreases with ageing.
24. To correct this type of defect of vision we need __________ which are formed using both concave and convex lenses.
25. The degree of convergence or divergence of light rays that can be achieved by a lens is expressed in terms of its ________.
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