In this post, you will get a complete solution for Class 10 Science Chapter 10 The human eye and the colourful world contains solutions of all intext and end exercise questions. These solutions will help the students of class 10 to understand concepts.
.png "RBSE Solutions for Class10 Science Chapter 10 The Human Eye and The Colourful World")
This post covers
complete syllabus and lets you secure the best results in RBSE and other board
exams
Chapter 10- The Human Eye and the Colourful World
Answers of Questions on Page 164
Q.1 What is meant by power of accommodation of the eye?
Answer
The
ability of eye lens to adjust its focal length is called accommodation of eye.
This adjustment of focal length of lens
occurs so frequently so that we cannot feel it.
Q.2 A person with a myopic eye cannot see objects beyond 1.2
m distinctly. What should be the nature of the corrective lens used to restore
proper vision?
Answer
A
myopic person requires a concave lens as corrective lens to restore the proper
vision.
Q.3 What is the far point and near point of the human eye
with normal vision?
Answer
For
human eye with normal vision, the far point is infinity and near point is 25
cm.
Q.4 A student has difficulty reading the blackboard while
sitting in the first row. What could be the defect the child be suffering from?
How can it be corrected?
Answer
The
student is suffering from myopia and the defect can be corrected using concave
lens of appropriate power.
Answers of End Exercise Questions
Q.1 The human eye can focus objects at different distances by
adjusting the focal length of the eye lens. This is due to
(a) persistence of vision
(b) accommodation
(c) near-sightedness
(d) far-sightedness
Answer (b) accommodation
Q.2 The human eye forms the image of an object at its
(a) cornea
(b) iris
(c) pupil
(d) retina
Answer (b) retina
Q.3 The least distance of distinct vision for a young adult
with normal vision is
(a) 25 m
(b) 2.5 cm
(c) 25 cm
(d) 2.5 m
Answer (c) 25 cm
Q.4 The change in focal length of an eye lens to focus the
image of objects at varying distances is done by the action of the
(a) pupil
(b) ciliary muscles
(c) retina
(d) blind spot
Answer (b) ciliary muscles
Q.5 A person needs a lens of power 5.5 diopters for
correcting his distance vision. For correcting his near vision, he needs a lens
power + 1.5 dioptre. What is the focal length of the lens required for
correcting (i) distance vision and (ii) near vision?
Answer
Q.6 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 enable him to see
very distance objects distinctly?
Answer
The
myopic lens can form a distinct image of an object at 80 cm.
∴ Object-distance (u) =
-80 cm = - 0.8 m.
For human eye image distance (v)
= +
0.02 m.
So, focal
length of myopic lens
So a concave lens of power – 1.25 D is required to see the very distant objects distinctly.
Q.7 Make a diagram to show how hypermetropia is corrected.
The near point of a hypermetropic eye is 1 m. What is the power of lens
required to correct this defect? Assume that the near point of the normal eye
is 25 cm.
Answer
In
hypermetropic, convex lens forms the image of normal point at near point.
Q.8 Why a normal eye is not able to see clearly the objects
placed closer than 25 cm?
Answer
To see
the nearby objects eye lens has the ability to adjusts the focal length to form
the image of the object at retina, but if distance of object is lesser than 25
cm, eye-lens cannot decrease its focal length further. So 25 cm is the minimum
distance of distinct vision. The rays coming from the object which is at a
distance less than 25 cm are not focused at the retina and the image of the
object appear blurred so the image cannot be seen clearly.
Q.9 What happens to the image distance in the eye when we
increase the distance of an object from the eye?
Answer
Image
is always formed at retina of the eye. When we increase the object distance,
ciliary muscles are relaxed and focal length of lens is increased to form the
image of distant object at retina.
Q.10 Why do stars twinkle?
Answer
Stars
are at infinite distance from the earth so they seem like pointed size object.
Twinkling of stars is based on atmospheric refraction. The stars emit their own
light which is called star light. Light rays coming from the stars passes
through different layers of atmosphere. The density and other physical
conditions of atmosphere are changing that’s why light ray from stars deviates
from their path and the stars seems twinkling.
Q.11 Explain why the planets do not twinkle.
Ans. The planets are much nearer than the stars, so
planets are considered as large source of light. They are considered as a
collection of large number of point sized sources of light, so they nullify the
twinkling effect.
Q.12 Why does the sun appear reddish early in the morning?
Ans. At
the time of sunrise and sunset, the sky in the east and the west appears
reddish because at this time the sun is near the horizon and the light from the
sun passes through the lower thick layers of atmosphere.
So the blue light get scattered away and
only light of longer wavelength (red light) reaches our eyes and sung and
surrounding sky appears red.
Q.13 Why does the sky appear dark instead of blue to an
astronaut?
Answer
The sky appears dark instead of blue to an
astronaut because there is no atmosphere containing air so there is no
scattering of light in the space.
RBSE Class 10 Science Questions Answers
Chapter | Chapter Name |
1 | |
2 | |
3 | |
4 | |
5 | |
6 | |
7 | |
8 | |
9 | |
10 | The Human Eye and the Colourful World |
11 | Electricity |
12 | Magnetic Effects of Electric Current |
13 | Our Environment |
.jpg)
.jpg)
.jpg)
No comments:
Post a Comment