CBSE Class 10 Science 2019 · Paper 31/2/3 · Question 6(b)
A student needs spectacles of power D for the correction of his vision.
- (i)Name the defect in vision the student is suffering from.
- (ii)Find the nature and focal length of the corrective lens.
- (iii)List two causes of this defect.
Answer
Myopia; a concave lens of focal length cm; causes are excessive curvature of the eye lens and elongation of the eyeball.
(i) Myopia (near-sightedness).
(ii) The power is negative, so the corrective lens is a concave (diverging) lens. Its focal length is m cm, that is, a concave lens of focal length cm.
(iii) (a) Excessive curvature of the eye lens; (b) Elongation of the eyeball.
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