Question 25
Explain the structure and functioning of human eye. How are we able to see nearby as well as distant objects?
Question 25
Explain the structure and functioning of human eye. How are we able to see nearby as well as distant objects?
Structure and functioning of the Human eye:
Cornea: The front part of the eye is covered by a transparent spherical membrane called the cornea. Light enters the eye through the cornea. The space behind the cornea is filled with a liquid called aqueous humor.
Iris: Just behind the cornea is a dark coloured muscular diaphragm which has a small circular opening in the middle.
Pupil: Pupil is the small circular opening of iris. The pupil appears black because no light is reflected from it.
Eye Lens: The eye lens is a convex lens made of a transparent jelly-like protein aqueous material. The eye lens is hard at the middle and gradually becomes soft towards the outer edges. The eye lens is held in position by ciliary muscles. The ciliary muscles help in changing the curvature and focal length of the eye lens.
Retina: The inner back surface of the eyeball is called retina. It is a semi-transparent membrane which is light sensitive and is equivalent to the screen of a camera. The light-sensitive receptors of the retina are called rods and cones. When light falls on these receptors they send electrical signals to the brain through the optic nerve. The space between the retina and eye lens is filled with another fluid called vitreous humor.
Blind spot: It is a spot at which the optic nerve enters the eye and is insensitive to light and hence the name.
Working: The light coming from an object enters the eye through cornea and pupil. The eye lens converges these light rays to form a real, inverted and diminished image on the retina. The light-sensitive cells of the retina get activated with the incidence of light and generate electric signals. These electric signals are sent to the brain by the optic nerves and the brain interprets the electrical signals in such a way that we see an image which is erect and of the same size as the object.
Structure and functioning of the Human eye:
Cornea: The front part of the eye is covered by a transparent spherical membrane called the cornea. Light enters the eye through the cornea. The space behind the cornea is filled with a liquid called aqueous humor.
Iris: Just behind the cornea is a dark coloured muscular diaphragm which has a small circular opening in the middle.
Pupil: Pupil is the small circular opening of iris. The pupil appears black because no light is reflected from it.
Eye Lens: The eye lens is a convex lens made of a transparent jelly-like protein aqueous material. The eye lens is hard at the middle and gradually becomes soft towards the outer edges. The eye lens is held in position by ciliary muscles. The ciliary muscles help in changing the curvature and focal length of the eye lens.
Retina: The inner back surface of the eyeball is called retina. It is a semi-transparent membrane which is light sensitive and is equivalent to the screen of a camera. The light-sensitive receptors of the retina are called rods and cones. When light falls on these receptors they send electrical signals to the brain through the optic nerve. The space between the retina and eye lens is filled with another fluid called vitreous humor.
Blind spot: It is a spot at which the optic nerve enters the eye and is insensitive to light and hence the name.
Working: The light coming from an object enters the eye through cornea and pupil. The eye lens converges these light rays to form a real, inverted and diminished image on the retina. The light-sensitive cells of the retina get activated with the incidence of light and generate electric signals. These electric signals are sent to the brain by the optic nerves and the brain interprets the electrical signals in such a way that we see an image which is erect and of the same size as the object.
