Monday, October 3, 2011

CBSE NCERT 10Th Humane Eyes and Colourfull world E-Notes

CBSE PHYSICS Class 10 Physics The Humane Eyes Notes:  IMPORTANT CONCEPTS:
Human eye can be treated as an optical instrument. Light rays coming from the object to be seen enter the eye through Cornea and fall on the eye lens through the pupil of the eye.
Eye lens being double convex lens forms a real inverted and smaller image of the object on the retina.
The retina contains numerous light sensitive cells which are activated by the light falling on the retina and generate electrical signals which are sent to brain via optic nerve and the brain processes this information and we perceive objects as they are.

The human eye has the following parts:-
(a) Cornea:-The transparent spherical membrane covering the front of the eye.
(b) Iris:-The coloured diaphragm between the cornea and lens.
(c) Pupil:-The small hole in the iris.
(d) Eye lens:-Its is a transparent lens made of jelly like material.
(e) Ciliary muscles:-These muscles hold the lens in position.
(f) Retina:-The back surface of the eye.
(g) Blind spot:-The point at which the optic nerve leaves the eye. An image formed at this point is not sent to the brain.
(h) Aqueous humour:-A clear liquid region between the cornea and the lens.
(i) Vitreous humour:-The space between eye lens and retina is is filled with another liquid called Vitreous humour.
Persistence of vision: The image of an object seen persists on the retina for 1/16 second even after the removal of the object. This continuance of sensation of eye for some timed is called persistence of vision.
Colour blindness: It is said to occur when a person cannot distinguish between colours though his vision may otherwise be normal.

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