CBSE Class 10 Science 2020 · Paper 31/5/1 · Question 24(a)
A student uses spectacles of focal length m.
- (a)Name the defect of vision he is suffering from.
- (b)Which lens is used for the correction of this defect ?
- (c)List two main causes of developing this defect.
- (d)Compute the power of this lens.
Answer
Myopia, corrected by a concave lens; causes are excessive curvature of the eye lens and elongation of the eyeball; D.
(a) Myopia (near-sightedness): the lens has a negative focal length, so it is a concave lens, the lens used to correct myopia.
(b) A concave (diverging) lens of suitable power.
(c) (i) Excessive curvature of the eye lens; (ii) elongation of the eyeball.
(d) D.
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