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c) Focal length of the lens
d) Distance of the candle from the eyes
7. Which part of the eye produces maximum refraction of light rays? 1
a) Retina
b) Cornea
c) Pupil
d) Lens
8. Diabetic retinopathy causes damage to blood vessels in the retina. Which of 1
the following would NOT happen in a person having diabetic
retinopathy?
a) Focussing on objects at different distances
b) Formation of a clear image of the object
c) Change in the size of the pupil
d) Entry of light into the eye
9. While walking along the riverbank, Trupti found a smooth, milky white 2
stone. When a ray of sunlight fell upon it, she observed that the stone
appeared bluish in colour and the light that passed through it appeared
orange in colour.
(a) Identify the phenomenon that Trupti observed as sunlight fell upon the
stone.
(b) How would the size of the stone particles compare to the wavelength of
visible light?
10. Presbyopia is a defect in vision. What is the primary cause of presbyopia? 2
How can we correct this defect?
11. Why do leaves appear green? 2
12. A person needs a lens of power 5.5 Dioptre for correcting his distinct vision. 3
For correcting his near vision, he needs a lens +1.5 Dioptre. What is the focal
length of the lens required for correcting:
(A) distinct vision, and
(B) near vision?
13. (A) What happens to the image distance in the eye when we increase or 3
decrease the distance of an object from the eye?
(B) Give reasons:
(i) There is no dispersion of light refracted through a rectangular glass slab.
(ii) There is no dispersion of light when a monochromatic light having only
one wavelength passes through a prism.
14. Nanda saw rays of sunlight entering into a dark room as shown below. 3
He then did something to the air in the room after which he was NOT able to
see the rays of sunlight in the room. What is it that Nanda could have done
to make the rays of sunlight invisible? Justify your answer.
15. Mars's atmosphere is composed mainly of carbon dioxide, nitrogen and 3
argon and negligible amounts of oxygen, water vapour and methane. Using
the information given in the sentence above and knowledge about how
rainbows are formed on Earth, explain why rainbow formation is impossible
on Mars.
16. Space is mostly vacuum, devoid of any medium. 3
(a) What colour does the Sun appear to the astronauts on International
Space Station?
(b) Give reason for your answer to (a).