Human eye work's

The individual components of the eye work in a manner similar to a camera. Each part plays a vital role in providing clear vision. So think of the eye as a camera with the cornea, behaving much like a lens cover. As the eye's main focusing element, the cornea takes widely diverging rays of light and bends them through the pupil, the dark, round opening in the center of the
colored iris. The iris and pupil act like the aperture of a camera.
Next in line is the lens which acts like the lens in a camera, helping to focus light to the back
of the eye. Note that the lens is the part which becomes cloudy and is removed during cataract
surgery to be replaced by an artificial implant nowadays. The very back of the eye is lined with a layer called the retina which acts very much like the film of the camera. The retina is a membrane containing photoreceptor nerve cells that lines the inside back wall of the eye. The photoreceptor nerve cells of the retina change the light rays into electrical impulses and send them through the optic nerve to the brain where an image is perceived. The center 10% of the retina is called the macula. This is responsible for your sharp vision, your reading vision. The peripheral retina is responsible for the peripheral vision. As with the camera, if the "film" is bad in the eye (i.e. the retina), no matter how goodt he rest of the eye is, you will not get a good picture.  The human eye is remarkable. It accommodates to changing lighting conditions and focuses light rays originating from various distances from the eye. When all of the components of the eye function properly, light is converted to impulses and conveyed to the brain where an image is perceived.

WHAT HAPPENS WHEN YOU CUT A MAGNET INTO PIECES?

Gather the following equipment: A hack saw and an inexpensive bar magnet.
Follow this procedure: 1. Saw the magnet into thirds. Put the magnet together again as it was by placing the pieces side by side.
You will observe:The parts of the magnet attract each other when you replace them exactly as they were before you sawed them apart.

2. Pull the two ends away from the middle. Turn them around so that what were the north and south poles of the unsawed magnet are now point-ing inward toward the center piece. Move them toward the center piece.
You will observe: The center piece repels each end piece.

3. Take each of the three pieces of the magnet in turn and place first one end and then the other about ~ of an inch from the hack-saw blade. You will observe: In each case the hack-saw blade is attracted to the magnet. When you cut or break a magnet, the cut or broken end becomes the opposite pole to the one on the other end. A broken magnet does retain its magnetic power, but striking, dropping or vibrating a magnet, as you did when you sawed it apart, weakens it con-siderably. Magnets also become weaker when they are heated. Bear this in mind, and remember to handle and store magnets with care.

Cold Air And Warm Air

MAGNETISM

                :: MAGNETISM ::

       Magnetism is the power of certain stones and   metals to attract each other. According to legend, the discovery of magnetism occurred about 3000 years ago in an ancient Middle Eastern country called Magnesia.

      One day, the story goes, a shepherd found it difficult to lift his iron-tipped staff from certain places on the ground. After investigating, he realized that he had difficulty only when the iron tip was on a certain type of dark stone. These stones were loadstones (sometimes spelled "lodestone") , which contain a kind of iron ore called magnetite.

    Since magnetism became known, man has found out much about this power and devised many uses for it. With the aid of science, he has also learned to impart magnetism to certain metals which do not possess it naturally.