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Q.

When light enter the human eye, it passes through the different parts of the eye. In this context arrange the following in the correct sequence:
Explanation:

ANSWER: (D) 

  • Human eye is the organ of vision of the human body that enables us to see. The human eyes are located in the specialized sockets carved out in the human skull. Each human eye is approximately 2.5 cm in diameter. The main parts of a human eye include sclera, cornea, retina, optic nerve, lens and so on.
  • Cornea is the transparent portion of our eye that allows the light to enter our eye and is made up of transparent tissue. The cornea refracts light and accounts for two-thirds of the eye’s total power.
  • The lens is a biconvex, transparent structure present in the eye behind the pupil. The lens along with the cornea refracts the light, so as to focus it on the retina. By changing its shape, the lens is capable of changing the focal distance of the eye.
  • The retina is a light-sensitive tissue in the inner coat of the eye that sends electrical signals after converting them from light to the brain for processing. Rods and cones are the two light-sensitive types of cells present in the retina. Rods help us for night-time vision and cones help us see colours.
  • The optic nerve sends electrical impulses from the retina, at the back of the eyes to the brain.
  • For light incidents on the eye, light enters the eye through the clear, dome-shaped surface that covers the front of the eye, the cornea. From the cornea, the light passes through the pupil. The iris is the coloured part of your eye that controls the amount of light passing through.
  • From there, it then falls on the lens, which then focuses light rays onto the retina.
  • Next, light passes through the vitreous humour that helps to keep the eye round in shape. Finally, the light reaches the retina, the light-sensitive nerve layer lining the back of the eye. Here the image is inverted. The optic nerve is then responsible for carrying the signals to the visual cortex of the brain. The visual cortex turns the signals into images.
  • Therefore, Light enters our eye through the cornea, the clear, curved layer in front of the iris and pupil. After passing through the cornea, light travels through the pupil which is surrounded by iris and behind the iris sits the lens which changes the shape and focuses light onto the retina then the photoreceptors in the retina convert the image into electrical signals, which are carried to the brain by the optic nerve.

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