Human Eye and Colourful world — Flashcards

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The eye lens helps form an image on the retina. It changes its focal length so that objects at different distances can be seen clearly.

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The cornea is the transparent protective membrane covering the front sharply curved portion of the eye ball. It is visible from outside.

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The pupil is the small hole in the iris. It appears black because light entering it goes into the eye and very little light comes back out.

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The iris expands the pupil in dim light so more light enters, and contracts the pupil in bright light so less light enters. It acts like a variable aperture.

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The retina is a delicate membrane at the back of the eyeball. It contains about 125 million rods and cones, and the real inverted image is formed here.

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Rods identify the intensity of light, while cones identify colour. Together they help the brain understand the image seen by the eye.

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The distance between the eye lens and retina is about 2.5 cm, so the image distance remains fixed. The eye adjusts its focal length to keep the image on the retina.

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Accommodation of lens is the ability of the eye lens to change its focal length.