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प्रश्न
How does the eye adjust itself to deal with light of varying intensity?
उत्तर
The iris regulates the amount of light entering the human eye by automatically adjusting the size of the pupil according to the intensity of light that the eye receives. If the intensity of light is high, the iris contracts the pupil so as to reduce the amount of light entering the eye. If the intensity of light is low, the pupil expands to allow more light to enter the eye.
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संबंधित प्रश्न
Write the function of the following part of the human eye: ciliary muscles
The human eye can focus objects at different distances by adjusting the focal length of the eye lens. This is due to ______.
A person got his eyes tested by an optician. The prescription for the spectacle lenses to be made reads :
Left eye : +2.50 D
Right eye : +2.00 D
State whether these spectacle lenses will converge light rays or diverge light rays.
What change is made in the eye to enable it to focus on objects situated at different distances? Illustrate your answer with the help of diagrams.
Why does the eye-lens not have to do all the work of converging incoming light rays?
Draw a diagram of the human eye as seen in a vertical section and label the parts which suit the following descriptions relating to the:
(i) photosensitive layer of the eye.
(ii) structure which is responsible for holding the eye lens in its position.
(iii) structure which maintains the shape of the eyeball and the area of no vision.
(iv) anterior chamber seen in front of the eye lens.
(v) outermost transparent layer seen in front of the eyeball.
Mention, if the following statement is True or False
Cones are the receptor cells in the retina of the eye sensitive to dim light.
In a relaxed state, the focal length of healthy eyes is _______.
Given below is a diagram depicting a defect of the human eye. Answer the questions that follow:
- Give the scientific term for the defect.
- Mention one possible reason for the defect.
- What type of lens can be used to correct the defect?
Write the main functional activity of the following structure.
Choroid
