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. Read more »
0 Comments
The electronic configuration of carbon is K=2, L=4. It has four electrons in the valence shell and belongs to group IV A (group 14) of the periodic table.
Carbon is a non metal. In nature, it occurs in its pure form as diamond and graphite. When fuels burn, the carbon in them reacts with oxygen to form carbon dioxide. Carbon circulates through air, plants, animals and soil by means of complex reactions. This is called carbon cycle.In the beginning of 19th century scientists classified the compounds of carbon into twotypes, based on their source of occurrence: i) Inorganic compounds (obtained from non living matter)ii) Organic compounds (obtained from living matter, such as plant and animal sources) however the basis of classification was subjected to alteration after wohler synthesis FRIEDRICH WOHLER : A creator of revolution in ORGANIC CHEMISTRY The term organic chemistry was used by the Swedish chemist Berzelius. This refers to the chemistry of living things. However, the German chemist Wohler succeeded in creating an organic compound (urea) from an inorganic compound (ammonium cyanate) in his laboratory. This has dealt a severe blow to the vital force theory (a theory of life process). MODERN DEFINITION OF ORGANIC CHEMISTRY DOWNLOAD FULL NOTES AND MORE |
Blog SeaRCH Link
All
Join Us For Update |