Detailed About Human Eye For SSC CGL,SSC CHSL And Railway Exams

Detailed About Human Eye For SSC CGL,SSC CHSL And Railway Exams
Detailed About Human Eye For SSC CGL,SSC CHSL And Railway Exams 
                                 Human Eye
       
        Defects of human eye and other remedies

1. Myopia or short sightedness: A person suffering from myopia can see the near objects clearly while far objects are not clear.
Causes:1. Elongation of eye ball along the axis.
      2. Shortening of focal length of eyes lens.
      3. over stretching of clearly muscles beyond the elastic limit.

Remedy:  Diverging lens is used\

2. Hyperopia or hypermetropia or long sightedness: A person suffering from hypermetropia can see The distant objects clearly but not the near objects.

Causes:1. shortening of eye ball along axis.
            2.Increase in the focal length of eye lens.
            3. Stiffening of ciliary muscles.

  Remedy: A converging lens is used

3.Presbyopia: This defect is generally found in elderly person. Due to stiffening of ciliary muscles, eye looses much of its accommodating power. As a result distinct as well as near by objects can not be seen.
For its remedy two separate lenses or a bifocal lens is used

4.Astigmatism: This defect arises due to difference in the radius of curvature of brought to focus by eye in another plane. For its remedy cylindrical lens is used.
There are two kinds of vision cells in the retina. They are called rods and cones on account to their peculiar shape. Rods decides the intensity of light where as cones distinguish colour of light.

                                           Theory of colours
Colours is the sensation perceived by the cones in the eye due to light

Primary colour: the spectral colours can be produced by mixing these in proper proportion.

 Blue + Red+ Green = White

Secondary Colour: The colour produced by mixing any two primary colours is a secondaryColour. There are three secondary yellow, magenta and Cyan as

  Green + Red = Yellow   Red + Blue = Magenta  Blue + Green += Cyan
When the three secondary colours are mixed, white colour is produced

  Yellow + Magenta + Cyan = white

Complementary colours: Any two Colours when added produce white light, are said to be Complementary colours. Clearly a secondary colour and the remaining Primary colours are Complementary colours. Red and Cyan, blue and Yellow and green and magenta are complementary each other.

  •   The different colours and their mixtures are shown by the colour triangle
  •  In coloured television, the three primary colours are used.

Colour of bodies: the colour of body is the colour of light which it reflects or transmits. An object is black if it absorbs the entire light incident over it. This is why a red rose appears red When viewed in white or red light but appears black when viewed blue or green.


Name of object
In white Light
In Red Light
In Green Light
In yellow Light
In Blue Light
White paper
White
Red
Green
Yellow
Blue
Red Paper
Red
Red
Black
Black
Black
Green Paper
Green
Black
Green
Black
Black
Yellow paper
Yellow
Black
Black
Yellow
Black
Blue Paper
Blue
Black
Black
Black
Blue

Detailed About Human Eye For SSC CGL,SSC CHSL And Railway Exams Detailed About Human Eye For SSC CGL,SSC CHSL And Railway Exams Reviewed by SSC-IBPS on 19:32:00 Rating: 5
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