why is the eyeball of human eye is black but the side of the eyeball is white?

Answer 1

The pupil (central part of the eye) is black because it is a hole. The hole allows in a certain amount of light, which hits the retina at the back of the eyeball and is then transferred to the brain via the optic nerve (this is what causes the 'blind spot' you sometimes get looking out of the corner of your eye. )

The coloured part of the eye - the iris - is actually a muscle (you can see the fibres if you look closely) controlling the light entering the eyeball.

The cornea (clear) and sclera (white) are colourless because they are the ONLY parts of the human body that have no blood flow (otherwise it would be opaque and you wouldn't be able to see out!).

This site may be of some use:

http://webvision.med.utah.edu/anatomy.html

Answer 2

The part of the eye you can see is in three parts, the white part called the Sclera is the firm, opaque,white, outer layer. It consists of dense collagenous connective tissue with elastic fibers. The sclera helps maintain the shape of the eye, protects the internal structures of the eye and provides an attachment point for the muscles that move the eye. The second part is the Iris this is the coloured part or the eye; its col or differs from person to person. Brown eyes have brown pigment in the iris, on the other hand, blue eyes are not caused by blue pigment but result from a scattering of light by the tissue of the iris in a fashion similar to the scattering of light as it passes through the atmosphere or water to form the blue skies and blue oceans. The iris is a contractile structure consisting mainly of smooth muscle and surrounding an opening called the pupil. The pupil appears black when you look into a person's eye because of the pigment in the choroid and the pigment portion of the retina. The eye is a closed chamber, emitting light only through the pupil, so looking into it is like looking into a dark room. If a bright light is directed into the pupil, however, the reflected light is red because of the blood vessels on the surface of the retina, which is why the pupils in the eyes of a person looking directly at a flash camera are red in the photograph.

Answer 3

Do you mean the iris or the pupil?

The pupil is the black part at the centre of your eye. It is actually a hole, covered by a lens. The reason it is black is that it opens into the inside of your eye and it's dark in there! When the pupil shows up red in photographs you are getting a reflection of the blood vessels at the back of the eye.

If you are asking why the iris of the eye is coloured (brown, blue etc) I have no idea if there is a scientific reason why this should be the case. The iris is essentially a springy diaphragm of tissue that is manipulated by muscles to increase or decrease the size of the pupil (its a bit like a hair scrunchie in form). The size of the pupil is varied to allow more or less light into the eye (which is why your pupil is bigger when you have been in a dark room).

Hope this answers your question :o)

Answer 4

the back of the eye absorbs light making it look black
The eyeball is sinuous cartilage that happens to be white,except after 10 beers.

Answer 5

The inside of the eye is actually red; that's why people get 'red eye' on photos. The pupil usually appears black because no light is being shone into it.

Answer 6

OK this is a wild guess.

The black is to allow the light in with out it being able to reflect in the back of your retina. Would probably get multiple or fuzzy images.
The white? hmm maybe due to no need of color.

I do know it is the fastest repairing organ in our body.

Answer 7

the black part is called the pupil and as light enters through your eye, the light rays fall onto the retina and it converts the light into a sense that we call it sight.
to tell you about this,you have to understand this. it's simple. you won't see a thing unless
1. a ray of light falls on it
2. a reflected ray of light that falls on object enters into your eye.

so, all the light falling on retina is not reflected back! so, you see no light coming back from retina under normal circumstances so you see nothing , only black thing!

and, the pupil is like a hole in a sphere. and the sclera, the white parts, are like the surface of the sphere.
light enters through the hole into the sphere and light falls on the surface, so you can see it!
and sclera is white due to its natural absent of pigmentation

Answer 8

It's not actully black, but it is like a hollow ball (well, it's actually not hollow, but filled with fluid, which is clear). It looks black because there is no light in there. It'd be like looking in a vase made of white porcelain. If you look in the hole, it looks dark inside, but the color of the inside isn't actually black.

Answer 9

the pupil (the black part) is a hole which light come in from (kind of like the hole in a camera for the picture. The white part is called the sclera.

Answer 10

The outer layer is white(sclera) but the one inside (Choroid) which contains the blood vessels etc is black.At the front of the eye the sclera becomes the clear cornea and the choroid becomes the coloured iris.