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Science · 2023 · 2 marks
CBSE 2023 · Region 1 · Set 1 · Q25
(a) A narrow beam XY of white light is passing through a glass prism ABC as shown in the diagram: Trace it on your answer sheet and show the path of…
A narrow beam XY of white light is passing through a glass prism ABC as shown in the diagram :
Trace it on your answer sheet and show the path of the emergent beam as observed on the screen PQ. Name the phenomenon observed and state its cause.
It is observed that the power of an eye to see nearby objects as well as far off objects diminishes with age.
(i)
Give reason for the above statement.
(ii)
Name the defect that is likely to arise in the eyes in such a condition.
(iii)
Draw a labelled ray diagram to show the type of corrective lens used for restoring the vision of such an eye.
Marking-scheme solution
(a) 
Dispersion of white light
Cause: Different colours of light bend through different angles w.r.t. the incident ray. / Different colours have different wavelengths.
(b) (i) It is due to gradual weakening of the ciliary muscles and diminishing flexibility of the eye lens.
(ii) Presbyopia/ Presbyopia + Myopia
(iii) Bifocal /Concave + Convex lens/ Diagram
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CBSE Class 10 Science past-paper question from the 2023 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.