NCERT Solutions for Class 10 Science Chapter 10 - The Human Eye and The Colorful World
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Did you ever wonder why the sky is blue in the daytime but reddish-orange during sunrise and sunset or why stars sparkle only at night? These are explained by Class 10 Science Chapter 10, The Human Eye and the Colorful World. Significant phenomena such as how our eyes work and defects of vision that occur commonly, how light is deviated (refraction), how white light spreads into its colours (dispersion), why stars sparkle, how light gets scattered, and the Tyndall effect are all described in this chapter of NCERT solutions.
This Story also Contains
- NCERT Solution for Class 10 Science Chapter 10 Solutions: Download PDF
- NCERT Class 10 Science Chapter 10: Intext Solutions
- NCERT Class 10 Science: The Human Eye and The Colorful World Exercise Solutions
- Class 10 Science NCERT Chapter 10: Higher Order Thinking Skills (HOTS) Questions
- NCERT Solutions for Class 10 Science Chapter 10: Important Topics
- NCERT Solutions for Class 10 Science Chapter 10: Important Formulae
- Benefits of NCERT Solutions for Class 10 Science Chapter 10
- NCERT Solutions for Class 10 Science: Chapter Wise
NCERT Solutions help students to learn these natural phenomena in more details, dispel some of the most widespread misconceptions and organize their studies properly so that they are able to pass their exams easily and successfully with the help of clear explanations and examples. The NCERT solutions for class 10 Science Chapter 10 contains: the PDF in form that can be downloaded, answers to intext questions, solutions to end of chapter exercises, Higher Order Thinking Skills (HOTS) questions, covers all the significant topics of this chapter.
NCERT Solution for Class 10 Science Chapter 10 Solutions: Download PDF
With step-wise answers to all questions in the textbook, the NCERT Solutions of Class 10 Science Chapter 10 The Human Eye and the Colourful World will make students understand the main points. These solutions are provided in form of a free downloadable PDF which is convenient and easy to revise.
NCERT Class 10 Science Chapter 10: Intext Solutions
NCERT Solutions Class 10 Science Chapter 10: Human Eye and the Colourful World (Intext Questions) offers precise explanations by illustrated diagrams to enable students to study certain principles involved in eye functioning, defects of the eyes, atmospheric refraction, and dispersion of light. These step-by-step solutions enhance clarity of concepts and helps in exam preparation.
Topic 10.2 - Defects of vision and their correction
Q. 1. What is meant by the power of accommodation of the eye?
Answer:
The power of accommodation is the ability of an eye to focus near and far objects clearly and make the image on the retina by adjusting its focal length. However, the focal length of the eye lens cannot be decreased below a certain minimum limit.
Answer:
The correction for a myopic eye should be the concave lens (negative power) to restore proper vision.
Q.3. What is the far point and near point of the human eye with normal vision?
Answer:
The far point of the human eye with normal vision is at infinity and the near point is 25cm distance from the eye.
Answer:
Since the student has difficulty reading the blackboard while sitting in the last row, he is most likely to suffer from myopia (short-sightedness), i.e., he can see objects clearly but is unable to see the far objects properly.
Hence, it can be corrected by placing the spectacles with concave lenses of appropriate power.
NCERT Class 10 Science: The Human Eye and The Colorful World Exercise Solutions
NCERT Solutions for Class 10 Science Chapter 10: The Human Eye and the Colourful World (Exercise Questions) offer well-structured answers to all textbook questions. These solutions simplify complex topics like vision, refraction, rainbow formation, and scattering of light, making them easier to understand and revise for exams.
(a) presbyopia
(b) Accommodation
(c) near-sightedness
(d) far-sightedness
Answer:
It is due to the accommodation of the eye. The human eye can adjust its focal length according to the different distances. Therefore, the option (b) is correct.
Q.2. The human eye forms the image of an object at its
(a) cornea
(b) iris
(c) pupil
(d) retina
Answer:
The human eye forms the image of an object at its retina. Therefore, the correct option is (d) Retina
Q.3. 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
Answer:
The least distance of distinct vision for a young adult with normal vision is about (c) 25 cm
Q.4. 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
Answer:
The change in focal length of an eye-lens is caused by the action of the :(c) ciliary muscles
Answer:
For the distant vision:
The power of the lens, given $P=-5.5 \mathrm{D}$
$
\operatorname{Power}(\text { in } D)=\frac{1}{f(m)}
$
Hence, the focal length will be:
$
f=\frac{100}{-5.5}=-18.2 \mathrm{~cm}
$
Therefore, the focal length of the lens required for correcting distant vision will be: -18.2 cm (Here, the negative sign of focal length tells us that it is a concave lens).
For near vision:
The power of the lens, given $P=+1.5 \mathrm{D}$
$
\operatorname{Power}(\text { in } D)=\frac{1}{f(m)}
$
Hence the focal length will be:
$
f=\frac{100}{+1.5}=66.66 \mathrm{~cm}
$
Therefore, the focal length of the lens required for correcting near vision will be: +66.7 cm (Here, the positive sign of focal length tells us that it is a convex lens).
Answer:
The myopic person is suffering from near-sightedness which can be corrected by putting the concave lens in spectacles.
Given the far point up to which a myopic person can see is 80cm in front of the eye.
Here, this person can see the distant object (kept at infinity) clearly if the image of this distant object is formed at his far point.
So, we have
The object distance, $u=\infty$ (in finity $)$
The image distance, $v=-80 \mathrm{~cm}$ (far point, in front of the lens).
Hence substituting the values in the lens formula: we obtain
$
\begin{aligned}
& \frac{1}{v}-\frac{1}{u}=\frac{1}{f} \\
& \Rightarrow \frac{1}{-80}-\frac{1}{\infty}=\frac{1}{f} \\
& \Rightarrow \frac{1}{f}=\frac{1}{-80}
\end{aligned}
$
$ \Rightarrow f=-80 \mathrm{~cm}$
Therefore, the focal length of the required concave lens will be 80 cm
Now, Power,
$
\text { Power }=\frac{1}{f(m)}=\frac{1}{-0.8}=-1.25 \mathrm{D}
$
Hence the power of the concave lens required is -1.25 D
Answer:
Given the near point for the hypermetropic eye is 1m.
Assume the near point of the normal eye is 25 cm.
So,
The object distance will be, $u=-25 \mathrm{~cm}$ (Normal near the point)
The image distance, $v=-1 m$ (Near the point of this defective eye) or -100 cm
Then the focal length can be found from the lens formula:
$
\frac{1}{v}-\frac{1}{u}=\frac{1}{f}
$
Substituting the values in the equation, we obtain
$
\begin{aligned}
& \Rightarrow \frac{1}{-100}-\frac{1}{-25}=\frac{1}{f} \\
& \Rightarrow \frac{-1+4}{100}=\frac{1}{f} \\
& \Rightarrow \frac{3}{100}=\frac{1}{f} \\
& \Rightarrow f=\frac{100}{3}=33.3 \mathrm{~cm} \text { or } 0.333 \mathrm{~m}
\end{aligned}
$
Hence the power of the lens will be:
$
P=\frac{1}{f(m)}=\frac{1}{+0.333 \mathrm{~m}}=+3.0 \mathrm{D}
$
Thus, the power of the convex lens required will be +0.3 D
Q.8. Why is a normal eye not able to see clearly the objects placed closer than 25 cm?
Answer:
A normal eye is not able to see clearly the objects placed closer than 25 cm because the ciliary muscles have a limit of contraction and relaxation, to see closer objects, ciliary muscles, must decrease the focal length of the eye lens. However, the focal length of the eye lens cannot be decreased below a certain minimum limit. Due to this, our eyes are not able to see objects clearly when placed closer than 25cm.
Answer:
There is no change to the image distance in the eye when we increase the distance of an object from the eye. The image is always formed in the retina of our eye.
Q.10. Why do stars twinkle?
Answer:
Stars twinkle because of turbulence in the atmosphere of the Earth.
The light from the star is refracted in different directions because of the variable refractive index. This seems to us like the position of stars to be changed slightly and also brightness and position, Hence, the twinkling of stars happens.
Q.11. Explain why the planets do not twinkle.
Answer:
Planets do not twinkle the way stars do, the reason is that stars are so far away that they appear to be a point source of light on the sky, while planets have finite size and the size of a planet "averages out" the turbulent effects of the atmosphere.
Therefore, we see a relatively stable image of the eye. Hence, twinkling is not observed on planets.
Q.12. Why does the Sun appear reddish early in the morning?
Answer:
At sunrise and sunset, the sun is closer to the horizon. The sunlight near the horizon passes through denser layers of the air and covers a larger distance before reaching our eyes. Most of the blue light gets scattered. The light that reaches our eyes is of longer wavelengths, mainly orange and red. That is why the sun appears red at sunrise and at sunset.
Q.13. Why does the sky appear dark instead of blue to an astronaut?
Answer:
The dark colour is nothing but the absence of light.
The sky appears dark instead of blue to an astronaut because there is no atmosphere in outer space that can scatter the sunlight. As the sunlight is not scattered, no scattered light reaches the eyes of the astronauts the sky appears black to them.
Class 10 Science NCERT Chapter 10: Higher Order Thinking Skills (HOTS) Questions
Class 10 Science Chapter 10 The Human Eye and the Colourful World (HOTS Questions) will assess in-depth knowledge and concept application. The questions are not basic ones because they make students develop their own way of thinking about the real-life phenomena, such as myopia, dispersion, and atmospheric refraction.
Q1: The angle of a prism is $30^{\circ}$ and its refractive index is $\sqrt{2}$ and one of the surface is silvered. At what angle of incidence, a ray should be incident on one surface so that after reflection from the silvered surface, it retraces its path?
Answer:
$\begin{aligned} & \text { so } r_1+r_2=A \\ & \text { and } r_2=0 \\ & \text { Hence } r_1=30^{\circ} \\ & n_1 \sin i=n_2 \sin r \\ & \Rightarrow \sin i=(\sqrt{2})(1 / 2) \\ & i=45^{\circ}\end{aligned}$
Q2: One ray of light suffers minimum deviation in an equilateral prism P additional prism Q and R of identical shape and made up of same material shown in figure. The ray will now suffer ________
Answer:
Atmospheric refraction causes the sun to appear two minutes before it is actually above the horizon (advanced sunrise). Also, we can see the sun for about two minutes even after it is actually below the horizon (delayed sunset). Therefore, the time from sunrise to sunset is increased by about four minutes because of the refraction of light through the earth's atmosphere. If the earth had no atmosphere, the length of the day would have been shorter by about four minutes.
Q3: Which of the following are conditions necessary for observing a rainbow?
Answer:
A rainbow occurs due to reflection and refraction occurring from water droplets present in the air. So, to see a rainbow, it should have rained and the Sun should be present.
At the same time, the Sun should be behind the observer. If it is otherwise, only the glare of the Sun will be felt and no rainbow will be observed.
Q4: A beam of white light falls on a glass prism. The colour of light which undergoes the least bending on passing through the glass prism is :
Answer:
$\mu=\frac{\text { velocity of light in air or vacuum }}{\text { velocity of light in a given medium }}$
The refractive index of violet colour in the glass is greater than the refractive index of red, in other words, the speed of violet is the least in glass and the speed of red is the highest. So, the red light bends the least while the violet the most.
Q5: By how much time the day would have been shorter if the earth had no atmosphere?
Answer:
Atmospheric refraction causes the sun to appear two minutes before it is actually above the horizon (advanced sunrise). Also, we can see the sun for about two minutes even after it is actually below the horizon (delayed sunset). Therefore, the time from sunrise to sunset is increased by about four minutes because of the refraction of light through the earth's atmosphere. If the earth had no atmosphere, the length of the day would have been shorter by about four minutes.
NCERT Solutions for Class 10 Science Chapter 10: Important Topics
NCERT Solutions Class 10 Science Chapter 10: The Human eye and the Colourful World have all the important topics like structure of the human eye, problems in vision, refraction in air, light scattering and formation of a rainbow. Students can learn the major concepts and successfully pass the exams with the utilization of these solutions.
10.1 The Human Eye
10.1.1 Power Of Accommodation
10.2 Defects Of Vision And Their Correction
10.3 Refraction Of Light Through A Prism
10.4 Dispersion Of White Light By A Glass Prism
10.5 Atmospheric Refraction
10.6 Scattering Of Light
10.6.1 Tyndall Effect
10.6.2 Why Is The Colour Of The Clear Sky Blue?
NCERT Solutions for Class 10 Science Chapter 10: Important Formulae
The Human Eye and the Colourful World NCERT Solutions Class 10 Science Chapter 10 also comprise a list of useful formulae on lens and refraction and vision correction. These solutions enable students to better solve numerical questions in less time and practice more in examination preparation.
1. Lens Formula
$
\frac{1}{f}=\frac{1}{v}-\frac{1}{u}
$
Where:
$f=$ focal length of the lens
$v=$ image distance
$u=$ object distance
(Sign convention applies)
2. Magnification by a Lens
$
m=\frac{h^{\prime}}{h}=\frac{v}{u}
$
Where:
$m=$ magnification
$h^{\prime}=$ height of the image
$h=$ height of the object
3. Refractive Index
$
n=\frac{\sin i}{\sin r}
$
Or,
$
n=\frac{c}{v}
$
Where:
$i=$ angle of incidence
$r=$ angle of refraction
$c=$ speed of light in vacuum
$v=$ speed of light in the medium
Approach to Solve Questions of Human Eye And Colorful World
- Understand the anatomy of the human eye – Study about structures like cornea, iris, lens, retina, etc.
- Understand defects and corrections of the eye – Myopia (concave lens), Hypermetropia (convex lens), Presbyopia (bifocal lens).
-
Learn accommodation – The capacity of the eye to accommodate lens shape to focus near and far objects.
-
Understand refraction using prism – Light is bent and separated into spectrum (dispersion).
-
Understand the effects of atmospheric refraction – Twinkling of stars, advanced sunrise, delayed sunset.
-
Understand scattering of light – Blue sky, red sunset phenomenon explained by scattering of shorter and longer wavelengths.
-
Label diagrams clearly – Eye, prism, spectrum diagrams assist in scoring marks.
-
Practice NCERT questions – In-text and exercise questions often appear in exams.
Benefits of NCERT Solutions for Class 10 Science Chapter 10
-
Conceptual Clarity: Complex concepts such as accommodation of the eye, scattering of light and dispersion have been explained in a language that anyone can understand making learning very effective.
-
Easy Exam Preparation: The in-text and exercise questions are all answered on the basis of the latest CBSE guidelines, which also can help students how questions actually appear in the board examination.
-
Step-by-Step Solutions: Examples of numerical problems on lens formula, magnification and power of lens are clearly provided step-to-step giving accuracy and confidence.
-
Higher Order Thinking Skills (HOTS) Questions: The chapter contains additional application-oriented questions that develop analytical abilities and aids in resolving complex-based questions in exams and competitive tests.
-
Revision Friendly: The short and organized solutions can be used in a last-minute revision before tests.
-
Real-Life Connections: Solutions bridges the gap between the knowledge the students read in the textbook and the real world by providing explanations to how rainbows form or why the sky is blue and why the sun appears to have a red color during sunset allowing the students to relate science to real life.
Also, check
- NCERT solutions for classes 6 to 12
- Human Eye and Colourful World NCERT Exemplar Solutions
- Human Eye and Colourful World NCERT Chapter Notes
NCERT Solutions for Class 10 Science: Chapter Wise
NCERT Solutions for Class 10 Science provide detailed explanations of every chapter, covering both Physics, Chemistry, and Biology topics. With step-by-step answers, important formulas, and extra practice questions, these solutions help students build strong concepts and prepare effectively for their CBSE board exams.
Frequently Asked Questions (FAQs)
Q: What is the human eye in Class 10?
A:
The human eye is a human optical instrument which resembles a camera. It helps us to see things by refracting the light through the cornea and the lens, which in turn produces the image on the retina. The retina turns the image into a series of electrical impulses, which are transmitted to the brain by the optic nerve, enabling us to see.
Q: Why do stars twinkle in Class 10 NCERT solutions?
A:
The twinkling is caused by the atmospheric refraction of light in stars. As starlight is refracted through the turbulent atmosphere of the Earth, it is continuously refracted because of the different densities of air and temperatures. This causes alternation of the apparent location of the star, which leads to the twinkling effect.
Q: How can I download NCERT solutions for class 10 Science chapter 10 pdf?
A:
Through the NCERT solutions Class 10 science chapter 10 PDF download facility, download this solution as a webpage to access offline. To get more problems on The Human Eye and The Colourful World, refer to the NCERT exemplar.
Q: How to solve human eye numericals?
A:
The numericals involving the human eye will be solved by first finding out the kind of eye defect. Measure the object distance (u) and image distance (v), and the smallest distance of clear vision was 25 cm, which is the least distance of distinct vision in a normal eye. Use the lens formula (1/f=1/v -1/u) to obtain the focal length (f). Subsequently, P = 1/f (f in meters) to derive the lens power. Lastly, test the sign of P: A positive value means that the lens used is convex to correct hypermetropia, whereas a negative value means that the lens used is concave to correct myopia.
Q: How human eye class 10 solutions is important for the board exam?
A:
The NCERT Solutions for Class 10 Science's "The Human Eye and the Colorful World" chapter is important for board exams as it covers a key aspect of the Science syllabus. The solutions provide a comprehensive explanation of the concepts, helping students to score well in the subject and prepare for internal assessments and tests. It is a valuable resource for students preparing for board exams.
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