Name the part of the eye :
(a) which controls the amount of light entering the eye.
(b) on which the image is formed.
(c) which changes the focal length of eye-lens.
Name the part of the eye :
(a) which controls the amount of light entering the eye.
(b) on which the image is formed.
(c) which changes the focal length of eye-lens.
(a) The parts are iris and pupil. Between the cornea and the lens, we have a muscular coloured diaphragm called iris, which has a small hole in it, called the pupil. Iris is the coloured part that we see in the eye. The size of the pupil varies with the help of iris. In the dim light, the size of the pupil increases with the help of iris to allow more light to enter the eye. In bright light,-the pupil contracts to allow less light to enter into the eye. In other words, the iris regulates the amount of light entering the eye by dilating the pupil in light of low intensity and contracting the pupil in high-intensity light.
(b) The innermost coating of the eye, covering the rear of the inner surface is the retina. It is the screen on which the image is formed by the eye lens. Retina contains a large number of nerve fibres and blood vessels and acts as a light sensitive screen to receive the images. The light-sensitive cells get activated upon illumination and generate electrical signals. The sensation of vision in the retina is carried to the brain by optic nerve fibres, which are more than one million.
c) By the action of ciliary muscles, The eye focus length is changed by the action of ciliary muscles.
This ciliary muscle helps to change the thickness of the flexible and soft muscles and changes the eye lens converging power.
(a) The parts are iris and pupil. Between the cornea and the lens, we have a muscular coloured diaphragm called iris, which has a small hole in it, called the pupil. Iris is the coloured part that we see in the eye. The size of the pupil varies with the help of iris. In the dim light, the size of the pupil increases with the help of iris to allow more light to enter the eye. In bright light,-the pupil contracts to allow less light to enter into the eye. In other words, the iris regulates the amount of light entering the eye by dilating the pupil in light of low intensity and contracting the pupil in high-intensity light.
(b) The innermost coating of the eye, covering the rear of the inner surface is the retina. It is the screen on which the image is formed by the eye lens. Retina contains a large number of nerve fibres and blood vessels and acts as a light sensitive screen to receive the images. The light-sensitive cells get activated upon illumination and generate electrical signals. The sensation of vision in the retina is carried to the brain by optic nerve fibres, which are more than one million.
c) By the action of ciliary muscles, The eye focus length is changed by the action of ciliary muscles.
This ciliary muscle helps to change the thickness of the flexible and soft muscles and changes the eye lens converging power.
