eVidyarthi

Main Menu
  • eVidyarthi
  • School English Medium
    • Class 6th
      • Maths Class 6
      • Science Class 6
      • Hindi Class 6
      • Vyakaran
      • English Class 6
      • English Grammar
      • Sanskrit Class 6
      • Geography Class 6
      • Civics Class 6
      • History Class 6
    • Class 7th
      • Maths Class 7
      • Science Class 7
      • Hindi Class 7
      • Vyakaran
      • English Class 7
      • English Grammar
      • Sanskrit Class 7
      • Geography Class 7
      • Civics Class 7
      • History Class 7
    • Class 8th
      • Maths Class 8
      • Science Class 8
      • Hindi Class 8
      • Vyakaran
      • English Class 8
      • English Grammar
      • Sanskrit Class 8
      • Geography Class 8
      • Civics Class 8
      • History Class 8
    • Class 9th
      • Maths Class 9
      • Science Class 9
      • Hindi Class 9
      • व्याकरण
      • English Class 9
      • English Grammar
      • Economics Class 9
      • Geography Class 9
      • Civics Class 9
      • History Class 9
      • Sanskrit Class 9
    • Class 10th
      • Maths Class 10
      • Science Class 10
      • Hindi Class 10
      • Vyakaran
      • English Class 10
      • English Grammar
      • Economics Class 10
      • Geography Class 10
      • Civics Class 10
      • History Class 10
      • Sanskrit Class 10
    • Class 11
      • Maths Class 11
      • English Class 11
      • Hindi Class 11
      • Accounts Class 11
      • Physics Class 11
      • Chemistry Class 11
      • Biology Class 11
      • Economics Class 11
      • Geography Class 11
      • History Class 11
      • Political Science Class 11
      • Sociology Class 11
    • Class 12
      • Maths Class 12
      • English Class 12
      • Hindi Class 12
      • Accounts Class 12
      • Physics Class 12
      • Chemistry Class 12
      • Biology Class 12
      • Economics Class 12
      • Geography Class 12
      • History Class 12
      • Political Science Class 12
      • Sociology Class 12
    • Close
  • School हिन्दी माध्यम
    • Class 6
      • Hindi Class 6
      • English Grammar
      • Vyakaran
      • गणित Class 6
      • विज्ञान Class 6
      • सामाजिक विज्ञान Class 6
      • English Class 6
      • संस्कृत Class 6
    • Class 7
      • Hindi Class 7
      • English Grammar
      • Vyakaran
      • गणित Class 7
      • विज्ञान Class 7
      • सामाजिक विज्ञान Class 7
      • English Class 7
      • Sanskrit Class 7
    • Class 8
      • Hindi Class 8
      • English Grammar
      • Vyakaran
      • गणित Class 8
      • विज्ञान Class 8
      • सामाजिक विज्ञान Class 8
      • English Class 8
      • Sanskrit Class 8
    • Class 9
      • Hindi Class 9
      • English Grammar
      • Vyakaran
      • गणित Class 9
      • विज्ञान Class 9
      • सामाजिक विज्ञान Class 9
      • English Class 9
      • Sanskrit Class 9
    • Class 10
      • Hindi Class 10
      • English Grammar
      • Vyakaran
      • गणित Class 10
      • विज्ञान Class 10
      • सामाजिक विज्ञान Class 10
      • English Class 10
      • Sanskrit Class 10
    • Class 11
      • गणित Class 11
      • English Class 11
      • Hindi Class 11
      • अर्थशास्त्र Class 11
      • भूगोल Class 11
      • इतिहास Class 11
      • राजनितिक विज्ञान
      • समाजशास्त्र Class 11
      • भौतिक विज्ञान Class 11
      • रसायन विज्ञान Class 11
      • जीव विज्ञान Class 11
    • Class 12
      • गणित Class 12
      • English Class 12
      • Hindi Class 12
      • अर्थशास्त्र Class 12
      • भूगोल Class 12
      • इतिहास Class 12
      • राजनितिक विज्ञान
      • समाजशास्त्र Class 12
      • भौतिक-विज्ञान Class 12
      • रसायन विज्ञान Class 12
      • जीव विज्ञान Class 12
    • Close
  • यूपी बोर्ड
    • Class 6
      • गणित Class 6
      • English Class 6
      • विज्ञान Class 6
      • सामाजिक विज्ञान Class 6
      • Hindi Class 6
      • Sanskrit Class 6
      • कृषि विज्ञान Class 6
      • गृहशिल्प Class 6
    • Class 7
      • गणित Class 7
      • English Class 7
      • विज्ञान Class 7
      • सामाजिक विज्ञान Class 7
      • Hindi Class 7
      • Sanskrit Class 7
      • कृषि विज्ञान Class 7
      • गृहशिल्प Class 7
    • Class 8
      • English Class 8
      • विज्ञान Class 8
      • सामाजिक विज्ञान Class 8
      • Hindi Class 8
      • Sanskrit Class 8
      • कृषि विज्ञान Class 8
    • Class 9
      • गणित Class 9
      • English class 9
      • विज्ञान Class 9
      • सामाजिक विज्ञान Class 9
      • हिंदी Class 9
      • संस्कृत Class 9
    • Class 10
      • गणित Class 10
      • English Class 10
      • विज्ञान Class 10
      • सामाजिक विज्ञान Class 10
      • हिंदी Class 10
      • संस्कृत Class 10
    • Class 11
      • English Class 11
      • इतिहास Class 11
      • रसायन विज्ञान Class 11
      • भौतिक विज्ञान Class 11
      • संस्कृत Class 11
      • हिंदी Class 11
    • Class 12
      • गणित Class 12
      • English Class 12
      • रसायन विज्ञान Class 12
      • भूगोल Class 12
      • समाजशास्त्र Class 12
      • नागरिक शास्त्र Class 12
      • हिंदी Class 12
    • Close
  • बिहार बोर्ड
    • Class 6
      • हिंदी Class 6
      • Vyakaran
      • English Grammar
      • गणित Class 6
      • विज्ञान Class 6
      • English Class 6
      • सामाजिक विज्ञान Class 6
      • Sanskrit Class 6
    • Class 7
      • हिंदी Class 7
      • Vyakaran
      • English Grammar
      • गणित Class 7
      • विज्ञान Class 7
      • English Class 7
      • सामाजिक विज्ञान Class 7
      • Sanskrit Class 7
    • Class 8
      • हिंदी Class 8
      • Vyakaran
      • English Grammar
      • गणित Class 8
      • विज्ञान Class 8
      • English Class 8
      • सामाजिक विज्ञान Class 8
      • Sanskrit Class 8
    • Class 9
      • हिंदी Class 9
      • Vyakaran
      • English Grammar
      • गणित Class 9
      • विज्ञान Class 9
      • English Class 9
      • सामाजिक विज्ञान Class 9
      • Sanskrit Class 9
    • Class 10
      • हिंदी Class 10
      • Vyakaran
      • English Grammar
      • गणित Class 10
      • विज्ञान Class 10
      • English Class 10
      • सामाजिक विज्ञान Class 10
      • Sanskrit Class 10
    • Close
  • एमपी बोर्ड
    • Class 6
      • हिंदी Class 6
      • Vyakaran
      • English Grammar
      • English Class 6
      • संस्कृत Class 6
      • गणित Class 6
      • विज्ञान Class 6
      • सामाजिक विज्ञान
    • Class 7
      • हिंदी Class 7
      • Vyakaran
      • English Grammar
      • English Class 7
      • संस्कृत Class 7
      • गणित Class 7
      • विज्ञान Class 7
      • सामाजिक विज्ञान
    • Class 8
      • हिंदी Class 8
      • Vyakaran
      • English Grammar
      • English Class 8
      • संस्कृत Class 8
      • गणित Class 8
      • विज्ञान Class 8
      • सामाजिक विज्ञान Class 8
    • Class 9
      • हिंदी Class 9
      • Vyakaran
      • English Grammar
      • गणित Class 9
      • संस्कृत Class 9
      • विज्ञान Class 9
      • सामाजिक विज्ञान Class 9
    • Class 10
      • हिंदी Class 10
      • Vyakaran
      • English Grammar
      • English Class 10
      • गणित Class 10
      • संस्कृत Class 10
      • विज्ञान Class 10
      • सामाजिक विज्ञान Class 10
    • Class 11
      • English Class 11
      • गणित Class 11
      • अर्थशास्त्र Class 11
      • भूगोल Class 11
      • इतिहास Class 11
      • राजनितिक विज्ञान Class 11
      • भौतिक विज्ञान Class 11
      • रसायन विज्ञान Class 11
      • जीव विज्ञान Class 11
      • समाजशास्त्र Class 11
    • Class 12
      • हिंदी Class 12
      • English Class 12
      • गणित Class 12
    • Close
  • छत्तीसगढ़ बोर्ड
  • English
    • Basic English Grammar
    • Basic English Speaking
    • English Vocabulary
    • English Idioms & Phrases
    • Personality Enhancement
    • Interview Skills
    • Close
  • Softwares
    • Microsoft Word
    • PhotoShop
    • Excel
    • Illustrator
    • PowerPoint
    • Close
Class 10th Science || Menu
  • MCQ Science Class 10
  • Notes Science Class 10
  • Important Questions Science Class 10
  • Previous Year Papers Science Class 10
  • Sample Papers Science Class 10
  • Question Answer Science Class 10
  • Book Science Class 10
  • Marking Scheme Science Class 10
  • Syllabus Science Class 10
  • Chemical Reactions and Equations
    • Chemical Reactions
    • Chemical Equations
    • Combination and Decomposition Reaction
    • Types of Displacement Reactions
    • Redox Reactions
    • Close
  • Acids, Bases and Salts
    • Introduction to Acids and Bases
    • Properties of Acids and Bases
    • Ph Scale and Its Importance
    • Important Chemical Compounds
    • Close
  • Metals and Non-metals
    • Physical Properties of Metals and Non-Metals
    • Chemical Properties of Metals
    • Metals in Nature
    • Metallurgy
    • Electrovalent Bonding of Metals
    • Close
  • Carbon and its Compounds
    • Covalent Bonding of Non-Metals
    • Introduction to Hydrocarbons
    • Properties of Hydrocarbons
    • Alcohols and Carboxylic Acids
    • Nomenclature of Organic Compounds
    • Close
  • Periodic Classification of Elements
    • Classification – Early Attempts
    • Modern Periodic Table of Elements
    • Close
  • Life Processes
    • Nutrition in Plants
    • Nutrition in Animals
    • Introduction to Respiration
    • Respiration in Humans
    • Excretion
    • Transportation in Plants
    • Transportation in Human
    • Circulatory System in Humans
    • Close
  • Control and Coordination
    • Central Nervous System in Humans
    • Nervous and Muscular Coordination
    • Chemical Coordination in Plants
    • Chemical Coordination in Animals
    • Close
  • How do Organisms Reproduce?
    • Reproduction and Its Kinds
    • Modes of Asexual Reproduction
    • Sexual Reproduction in Plants
    • Reproductive System in Humans
    • Sexual Reproduction in Humans
    • Close
  • Heredity and Evolution
    • Heredity and Variation
    • Evolution and Evidences of Evolution
    • Mechanism of Evolution
    • Evolution and Classification
    • Close
  • Light – Reflection and Refraction
    • Reflection of Light
    • Spherical Lens and Its Power
    • Lens Formulae
    • Refraction Through Spherical Lens
    • Refraction Through Glass
    • Refraction of Light
    • Mirror Formulae
    • Spherical Mirrors
    • Reflection by Spherical Mirrors
    • Close
  • The Human Eye and the Colourful World
    • Human Eye
    • Dispersion of Light
    • Scattering of Light
    • Atmospheric Refraction
    • Defects of Vision
    • Close
  • Electricity
    • Ohm’s Law
    • Current and Voltage
    • Heating Effect of Electric Current
    • Resistors in Series and Parallel
    • Close
  • Magnetic Effects of Electric Current
    • Magnetic Field
    • Magnetic Force
    • Electromagnetic Induction
    • Close
  • Sources of Energy
    • Conventional Sources of Energy
    • Non-Conventional Sources of Energy
    • Close
Share on WhatsApp

Science Class 10 Chapter 11 Question Answer

Human Eye and Colourful World

Solutions For All Chapters Science 10

NCERT TEXTBOOK Solutions for Class 10 Science

Question 1
The human eye can focus 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

Answer:

(b) Accommodation

Question 2
The human eye forms the image of an object at its

(a) cornea

(b) iris

(c) pupil

(d) retina

Answer:

(d) Retina

Question 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:

(c) 25 cm

Question 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:

(c) Ciliary muscles

Question 5
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, and (ii) near vision ?

Solution:

(i) ∵ Power of distant viewing part of the lens, P1= -5.5 D

∴ Focal length of this part, f1 = \frac { 1 }{ { p }_{ 1 } } = \frac { 1 }{ -5.5 }  m = -0.182 m = -18.2 cm

 

(ii) For near vision,

Question 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 correct the problem ?

Solution:

The remedial lens should make the objects at infinity appear at the far point.
Therefore, for object at infinity, u = ∞
Far point distance of the defected eye, ν = – 80 cm

Negative sign shows that the remedial lens is a concave lens.

Question 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 the lens required to correct the defect ? Assume that the near point of the normal eye is 25 cm.

Solution:
(i) The near point N of hypermetropic eye is farther away from the normal near point N.

(ii) In a hypermetropic eye, the image of nearby object lying at normal near point N (at 25 cm) is formed behind the retina.

(iii) Correction of hypermetropia : The convex lens forms a virtual image of the object (lying at normal near point N) at the near point N’ of this eye.

The object placed at 25 cm from the correcting lens must produce a virtual image at 1 m or 100 cm.
Therefore, u = – 25 cm, ν = 100 cm

The positive sign shows that it is a convex lens.

Question 8
Why is a normal eye not able to see clearly the objects placed closer than 25 cm ?

Answer:
At distance less than 25 cm, the ciliary muscles cannot bulge the eye lens any more, the object cannot be focused on the retina and it appears blurred to the eye, as shown in the given figure.

Question 9
What happens to the image distance in the eye when we increase the distance of an object from the eye ?

Answer:
The eye lens of a normal eye forms the images of objects at various distances on the same retina. Therefore, the image distance in the eye remains the same.

Question 10
Why do stars twinkle ?

Answer:
Stars appear to twinkle due to atmospheric refraction. The light of star after the entry of light in earth’s atmosphere undergoes refraction continuously till it reaches the surface of the earth. Stars are far away. So, they are the point source of light. As the path of light coming from stars keep changing, thus the apparent position of stars keep changing and amount of light from stars entering the eye keeps twinkling. Due to which a star sometimes appear bright and sometimes dim, which is the effect of twinkling.

Question 11
Explain why the planets do not twinkle ?

Answer:
The planets are much nearer to the earth than stars and because of this they can be considered as large source of light. If a planet is considered to be a collection of a very large number of point sources of light, then the average value of change in the amount of light entering the eye from all point size light sources is zero. Due to this the effect of twinkling is nullified.

Question 12
Why does the sun appear reddish early in the morning ?

Answer:
The light coming from the sun passes through various denser layers of air in the earth’s atmosphere before reaching our eyes near the horizon. Most of the part of blue light and light of small wavelength gets scattered by dust particles near the horizon. So, the light reaching our eyes is of large wavelength. Due to this the sun appears reddish at the time of sunrise and sunset.

Question 13
Why does the sky appear dark instead of blue to an astronaut ?

Answer:
As an astronaut moves away from the atmosphere of earth, the atmosphere becomes thin. Due to the absence of molecules (or dust particles) in air, the scattering of light does not take place. Thus, sky appears dark in the absence of scattering.

NCERT Intext Questions  for Class 10 Science Page Number: 190

Question 1
What is meant by power of accommodation of the eye ?

Answer:
The power of accommodation of the eye is the maximum variation of its power for focusing on near and far (distant) objects.

Question 2
A person with a myopic eye cannot see objects beyond 1.2 m distinctly. What should be the type of the corrective lens used to restore proper vision ?

Answer:

Concave lens.

Question 3
What is the far point and near point of the human eye with normal vision ?

Answer:
For a human eye with normal vision the far point is at infinity and near point is 25 cm from the eye.

Question 4
A student has difficulty reading the blackboard while sitting in the last row. What could be the defect the child is suffering from ? How can it be corrected?

Answer:
The child is suffering from myopia. The child should use concave lens of suitable focal length.

Question Answer of Chapter in PDF

NCERT Book, Notes & MCQ Online Test

Online Quiz for Objective Questions in Hindi and English

ads

Android APP

eVidyarthi

YouTube Channels

Mathematics Class 6
Science Class 6
Social Science Class 6
हिन्दी Class 6
सामाजिक विज्ञान कक्षा 6
विज्ञान कक्षा 6

Mathematics Class 7
Science Class 7
SST Class 7
सामाजिक विज्ञान कक्षा 7
हिन्दी Class 7

Mathematics Class 8
Science Class 8
Social Science Class 8
हिन्दी Class 8

Mathematics Class 9
Science Class 9
English Class 9

Mathematics Class 10
English Class 10

Mathematics Class XI
Chemistry Class XI
Accountancy Class 11

Accountancy Class 12
Mathematics Class 12

Learn English
English Through हिन्दी
Job Interview Skills
English Grammar
हिंदी व्याकरण - Vyakaran
Microsoft Word
Microsoft Excel
Microsoft PowerPoint
Adobe PhotoShop
Adobe Illustrator
Learn German
Learn French
IIT JEE
Privacy Policies, Terms and Conditions, Contact Us
Copyright © 2023 eVidyarthi and its licensors. All Rights Reserved.