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Question
The diagram alongside represents a certain defect of vision of the human eye.
(i) Name the defect.
(ii) Describe briefly the condition in the eye responsible for the defect.
(iii) Redraw the figure by adding a suitable lens correcting the defect. Label the parts through which light-rays pass.
(iv) What special advantage do human beings derive in having both eyes facing forward?
Solution
(i) Hypermetropia.
(ii) There are two main conditions in the eye which is responsible for this defect :
1. Shortening of the eyeball from front to back.
2. The lens is less concave.
(iii) Correction of Hypermetropia:
(iv) Both the eyes facing forward helps in judging the depth or relative distance. This is due to overlapping images formed in brain from both eyes which focus on an object together at one time.
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