CBSE - Class 10 Science The Human Eye and the Colourful World Worksheet
1.
Why does the sky appear dark instead of blue to an astronaut?
2.
Why is a normal eye not able to see clearly the objects placed closer than 25 cm?
3.
The change in focal length of an eye lens is caused by the action of the
a.
pupil.
b.
retina.
c.
ciliary muscles.
d.
iris.
4.
What happens to the image distance in the eye when we increase the distance of an object from the eye?
5.
The least distance of distinct vision for a young adult with normal vision is about
a.
25 m.
b.
2.5 cm.
c.
25 cm.
d.
2.5 m.
6.
Why do stars twinkle?
7.
The human eye forms the image of an object at its
a.
cornea.
b.
iris.
c.
pupil.
d.
retina.
8.
Explain why the planets do not twinkle.
9.
The human eye can focus on objects at different distances by adjusting the focal length of the eye lens. This is due to
a.
presbyopia.
b.
accommodation.
c.
near-sightedness.
d.
far-sightedness.
10.
Make a diagram to show how hypermetropia is corrected. The near point of a hypermetropic eye is 1 m. What is the power of the lens required to correct this defect? Assume that the near point of the normal eye is 25 cm.
11.
The far point of a myopic person is 80 cm in front of the eye. What is the nature and power of the lens required to correct the problem?
12.
A person needs a lens of power $-5.5$ dioptres for correcting his distant vision. For correcting his near vision he needs a lens of power $+1.5$ dioptre. What is the focal length of the lens required for correcting (ii) near vision?
13.
A person needs a lens of power $-5.5$ dioptres for correcting his distant vision. For correcting his near vision he needs a lens of power $+1.5$ dioptre. What is the focal length of the lens required for correcting (i) distant vision?
