Extra Questions for Class 10 Science Chapter 11 Human Eye and Colourful World with Answers Solutions. (i) most relaxed Students who are in Class 10 or preparing for any exam which is based on Class 10 Science can refer NCERT Book for their preparation. It is produced by dispersion of sunlight by tiny water droplets, present in the atmosphere. Spreading of light in various directions by colloid particles. → Located in eye sockets in skull. → The refractive index of earth’s atmosphere in general increases from top to bottom. Defects of vision and their correction. State its cause. Answer: Human Eye and Colourful World - Know the working of a human eye, the difference between Cornea and Retina. Question 7. → Sometimes a person may suffer from both myopia and hypermetropia. … The ciliary muscles of a normal eye are in their The atmospheric refraction of light occurs in a medium of gradually changing refractive index. Question 6. The colour blind persons do not possess cone cells that respond to certain colours. How did Newton, using two identical glass prisms, show that white light is made of seven colours? Answer: How does this happen? Parts of Human Eye • Cornea: It is the outermost, transparent part. Class 1 - 3; Class 4 - 5; Class 6 - 10; Class 11 - 12; CBSE. Human Eye and Colourful World class 10 Notes. The ability to see is called vision. A collection of questions on CBSE- Human Eye and the Colourful World with solutions created by best teachers are available as a PDF download. Which defect of the eye can be corrected by using a cylindrical lens? Answer: Question 23. (ii) Near point or 25 cm. Since we see the blue light from everywhere overhead, the sky appears blue. Question 19. Or (b) A glass prism is able to produce a spectrum when white light passes through it but a glass slab does not produce any spectrum. Question 4. • Three phenomenon which are involved in rainbow formation are : → Some water droplets remain suspended in air after rain. This defect can be corrected by using cylindrical lenses of suitable focal length and suitable axis in the spectacles. Question 4. Question 1. The phenomenon in which a part of the light incident on a particle is redirected in different directions is called the scattering of light. Find the nature, the focal length and the power of the correcting lens. (ii) correction of myopia using a lens. The defect of the vision is hypermetropia. Question 20. Danger signal lights are red in colour because the red coloured light having longer wavelength is scattered the least by fog or smoke. → Human eye: The sense organ that helps us to see. This ability of the human eye is called the power of accommodation of human eye. When a monochromatic light having only one wavelength, passes through a prism, will it show dispersion? Human Eye and Colourful World Class 10 Important Questions Short Answer Type I. Answer: b. What is colour blindness? In the following diagram, the path of a ray of light passing through a glass prism is shown below. Dispersion of White Light by Glass Prism. So, the sky appears blue. Answer: As a result, the cornea has different curvatures in different directions of the horizontal and vertical planes. Therefore, the sky appears blue from the surface of the Earth. Answer: (ii) Stars near the horizon appear slightly higher than their actual position. So, danger signs are made in red colour. What causes presbyopia? → When light enters the rain drop, it first refracts and disperses. A person can see clearly only up to 3 metres. As rays of all colours emerge in the same direction, i.e., the direction of the incidence of white light, there is no dispersion. Explain why it is so. A collection of questions on CBSE- Human Eye and the Colourful World with solutions created by best teachers are available as a PDF … The far point of a normal human eye is at infinity. What do you understand by spectrum of white light? In the bright sunlight, iris causes the pupil to become smaller so that only a small portion of light enters the eye and rods of the retina are also adjusted in the same way. As the object approaches from infinity towards the eye, the focal length of the eye lens decreases (or vice-versa) so as to maintain the same image distance. → The upper layer of atmosphere contains very fine particles of water vapours and gases. Answer: What eye defect is hypermetropia? The Human Eye and Its Structure ‘Human Eye’ is the organ of vision of the human body that enables us to see. What is meant by ‘persistence of vision’? Answer: NCERT Exemplar Class 10 Science Unit 11 Human Eye and Colourful World. Answer: Focal length increases. Answer: How does refraction of light take place in the atmosphere? During sunset and sunrise, the sun is near horizon and therefore the sunlight has to travel larger distance in atmosphere. ... CBSE Previous Year Question Papers Class 10 Science; CBSE Previous Year Question Papers Class 12 Physics; CBSE Previous … (a) Myopia is the defect of the eye vision due to which a person can see the nearly objects clearly but cannot see the far objects so distinctly. At the time of sunrise and sunset, when the Sun is near the horizon, sunlight travels a greater distance through the atmosphere to reach us. Find the nature, the focal length and the power of the correcting lens used for the defective vision. The water droplets act like small prisms. Question 16. Answer: Studyrankers is a free educational platform for cbse k-12 students. (b) A glass slab acts as a combination of two identical glass prisms. Answer: Seven colours of spectrum are violet, indigo, blue, green, yellow, orange and red also known as ‘VIBGYOR’. Why there is no dispersion of light refracted through a rectangular glass slab? Hypermetropia (Long-sightedness): A person can see distant objects distinctly but cannot see nearby objects so clearly in this case, the image is formed behind the retina. A planet is considered as a collection of large number of point sized sources of light, the total variation in the amount of light entering our eye from all individual point sized sources will average out to zero, thereby nullifying the twinkling effect. NCERT Exemplar for Class 10 Science Chapter 11 The Human Eye and The Colourful World Multiple Choice Questions 1. This enables us to see nearby objects clearly. The + sign with for the power indicates a convergent lens. CBSE Class-10 Revision Notes and Key Points. What is meant by advance sunrise and delayed sunset. It is also called eyesight. This is called internal reflection. This increases the curvature of the eye lens. Bifocal lens is required to improve the vision. By using two identical prism, one placed inverted with respect to the other we get a narrow beam of white lgiht incident on one prism emerges out of the second prism as white light. So he can see the objects clearly only in one plane. (c) What is the nature of the corrective lens? Question 8. Pupil: To regulate and control the amount of light entering the eye. Astigmatism. 2. Download free CBSE Sample paper for Class 10, Physics. Answer: No, it will not show dispersion. → Red is the least deviated colour as it has largest/longest wavelength. Due to this, the slightly different images of the successive pictures present on the film merge smoothly with one another and give us the feeling of continuity and moving images. Question 6. Image Formation by Concave Mirror. → Use of convex lens of suitable power can correct the defect. Why does the sky appear dark to astronauts? Use this phenomenon to explain why the clear sky appears blue or the sun appears reddish at sunrise. Colour blindness is that defect of the eye due to which a person is unable to distinguish certain colours, sometimes even the primary colours. Answer: (ii) Path of light becomes visible when light passes through dense canopy of trees in a forest. A detailed explanation of the human eye along with its structural representation covering the important parts is mentioned in the chapter. The human eye is the natural convex lens that refracts light. Solution: Question 8. → The air above hot surface becomes hot and rises. This is why sun appear red in colour. In this defect, a person cannot focus on both horizontal as well as vertical lines at the same time. (i) Cornea Dispersion of light concept is made understandable in a simple way. Question 13. State the functions of each of the following parts of the human eye: These are more effective in scattering light of shorter wavelengths at the blue end than light of longer wavelengths at the red end. Human Eye: working of human eye, Persistence of vision, Power of accommodation of human eye, Defects of vision. (iii) Even larger particles scatter all the colours of light that is why it appears white. When sunlight passes through the atmosphere, the fine particles in air scatter the blue colour more strongly than red. Causes of hypermetropia: This defect arises because either: Hypermetropia can be corrected by using convex lens of suitable focal length in spectacles. (a) What is myopia? Explain, why a normal eye is not able to see distinctly the objects placed closer than 25 cm. ... Illustrate your answer by drawing ray diagram to show the formation of image by (i) a hypermetropic eye,(ii) a hypermetropic eye corrected with a suitable lens. So, light reaching us directly from the rising or setting Sun consists mainly of the longer wavelength red colour because of which the Sun appears red. When we look at the sky, the scattered light enters our eyes which majorly contains blue, colour and hence the sky appears blue. Human Eye and Colourful World. Question 11. Explains the various defects that happen for human and also describes the ways to correct it. What is Tyndall effect? Question and Answer forum for K12 Students. The tiny dust particles present in the air of room scatter the beam of light all around the room. Answer: Solution: NCERT Books. What should the appearance of the sky be during the day for an astronaut staying in the international space station orbiting the Earth? → While sunset and sunrise, the colour of the sun and its surrounding appear red. The human ear is an important organ of the human body responsible for hearing and balance. State the objectives of organising such campaigns in schools. Question 18. Answer: We can contribute by participating in different ways of motivating people for the noble cause of eye donation such as, street play, banners, poster, door to door campaign, etc. The near point of an eye is also known as the least distance of distinct vision. Question 10. NCERT Solutions for Class 10 Science Chapter 11: The Human Eye and Colourful World. How is presbyopia corrected? The first prism splits the white light into its seven colour components. When a beam of light enters a smoke-filled dark room through a small hole, then its path becomes visible to us. The name of the defect is Presbyopia. Explain why the image distance in the eye does not change when we change the distance of an object from the eye? Under these conditions, the image of one picture persists on the retina of the eye till the image of the next picture falls on the screen, and so on. Question 15. This defect is then corrected by using bi-focal lenses of suitable focal lengths. (b) What is the focal length of the corrective lens? Describe the formation of rainbow in the sky with the help of a diagram. All colours of light travel at the same speed in a vacuum. Each human eye sizes for approximately 2.5 cm in diameter. Answer: Question 12. → This results in fluctuation of apparent position of star. Explain the structure and function of such a lens. Question 3. (a) What kind of defect in vision is she suffering from? Human Eye and Colourful World Extra Questions Very Short Answer Type. Therefore, it can be seen clearly from a distance. (ii) Medium sized particles scatter mainly the red colour (longer wavelength). Retina: To act as a screen to obtain the image of object and generate electrical signals which are sent to the brain via optic nerves. The fine particles in the atmosphere scatter light of shorter wavelength (blue colour) more strongly than the light of longer wavelength (red colour). The near point of a normal human eye is at a distance of 25 centimetres from the eye. For an astronaut, the sky would appear dark because in space there is no atmosphere to scatter light. (b) Curvature increrases. State one role of ciliary muscles in the human eye. Human Eye Diagram class 10 | How to Draw Human Eye Diagram … CBSE quick revision note for Class-10 Science, Chemistry, Maths, Biology and other subject are very helpful to revise the whole syllabus during exam days. When these colour components fall on the second prism, it recombines them to form white light. Formation of Rainbow. Your school has organised a campaign in the school and its neighbourhood in order to creat awareness about this fact and motivate people to donate their eyes after death. (b) The ability of the eye lens to adjust its focal length is called automatic accommodation. due to decrease in the focal length of the eye lens. What do you mean by power of accommodation of an eye? NCERT Solutions for Class 10 explains the detailed structure of the human eye. Using the phenomenon of scattering of light, explain why there is a difference in the colour of the sun as it appears during sunrise and at noon. What is hypermetropia (far-sightedness)? It provides most of the refraction of light. (i)  Apparent flickering of objects placed behind a hot object or fire. Question 7. Power of Accommodation of Human Eye: The human eye can clearly see a nearby object as well as an object on infinity. As these slow down by different amounts, different colours are refracted through different angles which causes dispersion. Near point or Least distance of distinct vision, Advantage of the eyes in front of the face. Defects of Vision in Eye (Myopia) Defects of Vision in Eye (Hypermetropia) Refraction of Light through a Glass Prism. Question 5. A Glimpse of CBSE Class 10 Science Marking Scheme This enables us to see distant objects clearly. Class 10 Class 12. A person is advised to wear spectacles with convex lenses. Power of Accommodation: The ability of an eye to focus the distant objects as well as the near by objects on the retina by changing the focal length is called power of accommodation. (c) Concave lens. The Human Eye: It is a natural optical instrument which is used to see the objects by human beings. Far-sightedness/Long-sightedness/Hypermetropia. The eye lens becomes thicker. Draw a ray diagram to show the path of a narrow beam of white light, through a combination of two identical prisms arranged together in inverted position with respect to each other, when it is allowed to fall obliquely on one of the faces of the first prism of the combination. The dispersion of white light occurs because different colours of light bend through different angles with respect to the incident ray, as they pass through a prism. Causes of myopia: Myopia is caused: Myopia can be corrected by using a concave lens of suitable focal length in the spectacles of such a person. What type of defect of vision is he suffering from? Solution: (a) Lens becomes thin the eyeball becomes too short, so that light rays from the nearby object, say at point N, cannot be brought to focus on the retina to give a distinct image. Why is the colour of sky blue? Question 9. With the help of labelled ray diagrams show The person with … → So rays bend towards the normal. It is for this reason that the sun is visible to us a little before it rises above the horizon and so also till a little later it sets below the horizon. Answer: → It is done by using concave lens of appropriate power. It is due to persistence of vision that we are able to see movie pictures in a cinema hall. → The sky would appear dark to an astronaut in the space as scattering is not very prominent at such high altitude due to absence of particles. → Diameter of eye ball – 2.3 cm. → Since the physical conditions of the earth’s atmosphere are not constant the light from. He would find that for all angles of incidence the ray of light bends: ... We hope the given NCERT MCQ Questions for Class 10 Science Chapter 11 Human Eye and Colourful World with Answers Pdf free download will help you. Question 22. In this diagram, the angle of incidence, the angle of emergence and the angle of … The light of shorter wavelength (blue) of the visible spectrum is scattered more than the light of longer wavelength by the atmospheric particles. → Both these effects are responsible for twinkling of stars. State the two causes of myopia. Answer: Question 17. A man with spectacles can read a book placed at 25 cm. In fact the sensation produced by the image of an object lasts for nearly 1/16th of a second on retina. Curvature decreases. The defect of the eye due to which a person is unable to distinguish between certain colours, is known as colour blindness. When a ray of light falls on water drop (or raindrop) it undergoes refraction and dispersion to form a spectrum. What causes astigmatism? The refractive index of hot air is less than that of cool air. The defect of vision is myopia. The upper part of the lens is a concave lens which corrects myopia to see the distant objects clearly, while the lower part of the lens has convex lens which corrects the hypermetropia to see the nearby objects clearly. Explain giving a reason why the sky appears blue to an observer from the surface of the Earth. This phenomenon is called dispersion. BOOK FREE CLASS; COMPETITIVE EXAMS. CBSE Previous Year Question Paper for Class 10, CBSE Previous Year Question Paper for Class 12. → Red is the least scattered colour. Question 2. This reduces the vision in old age. This is due to. Answer: Question 2. A person needs a lens of power -4.5 D for correction of her vision. The molecules of air and other fine particles in the atmosphere have size smaller than the wavelength of visible light. The human eye(s) are located in the specialized sockets carved out in the human skull. → Focal length of the eye lens becomes too long. The lens used in the spectacles has power – 2.0 D. The man without spectacles can read the book placed at which distance? NCERT Book for Class 10 Science Chapter 11 Human Eye and Colourful World is available for reading or download on this page. → The amount of light coming from stars also vary due to changing Refractive Index of atmosphere. The human eye structure and function makes it easy to distinguish the objects based on colour, size and other parameters. All the seven colours combined by the inverted prism and emerged as white light. A rainbow is a natural spectrum appearing in the sky Raindrop after a rain. What is the cause of dispersion? The second prism can be considered to be placed in an inverted position with respect to the first. (i) Concave mirror Answer: A rainbow is a natural spectrum appearing in the sky … Question 25. The revision notes covers all important formulas and concepts given in the chapter. How does atmospheric refraction affect sunrise and sunset? Most deviated component: Violet. This disease can be cured by replacing the defective cornea with the cornea of a donated eye. Question 11. In bifocal lens, upper portion is of concave or diverging lens to view far off objects and lower part is of convex or converging lens to view nearby objects. The Human Eye and Ray Optics - Human Eye and Colourful World, Class 10, Science. However, there is lateral displacement. What is astigmatism? The nearest point up to which the eye can see an object clearly without any strain, is called the near point of the eye. Answer: For most people, the near point gradually recedes and the far point comes closer. Here, v= -3 m, u = -12 m, f = ? (i) Path of light becomes visible when light enters a dark and dusty room through a slit or ventilator. Name the type of lens required by such persons to improve the vision. Such a person may suffer from myopia and hypermetropia. Question 21. What is colour-blindness? A person is advised to wear spectacles with concave lenses. Structure of Eye. Student sitting at the back bench in a class is not able to see what is written on the blackboard. Question 1: What kind of lens is present in the human eye ? Function of Ear. Cataract can be cured by eye surgery. Answer: The layers of air nearer to earth are denser than those above it. Explore the structure of the ear and its functions only at BYJU’S. Hence shorter waves are scattered .. away and longer (red) waves reach our eye. At sunrise, light from the sun near the horizon passes through thicker layers of air and larger distance in the earth’s atmosphere before reaching our eye. When these enter a transparent substance like prism, all slow down by different amounts depending on their wavelength. To the observer O these rays appear to come from B which is above horizon. Answer: Question 4. What kind of retinal cells are lacking in person suffering from this defect? Question 5. Human Eye and Colourful world Class 10 Important Questions with Answers Science Chapter 11 Human Eye and Colourful world Class 10 Important Questions Short Answer Type. → So, the light coming from a star near the horizon has to travel from rarer to denser medium and it bends towards the normal. Here, tiny water droplets in the mist scatter light. Due to gradual weakening of ciliary muscles and diminishing flexibility of the eye lens a certain defect of vision arises. Why are ‘danger’ signal lights red in colour? The power of accommodation of the eye decreases with ageing. (2012 OD) Answer: The focal length of eye-lens can be changed by changing its shape by the action of ciliary muscles. A student is observing the diagram showing the path of a ray of light passing through a glass prism. Write two causes for development of this defect. This is possible only when you have the best CBSE Class 10 Science study material and a smart preparation plan. lamge distance in the eye is the distance between the eye lens and the retina and it is fixed. Class 10 Science The Human Eye and the Colourful World – Get here the Notes for Class 10 Science The Human Eye and the Colourful World. (a) The splitting up of white light into its constituent colours on passing through a refracting medium like a glass prism is called dispersion of light. It is least scattered by fog and smoke and can be seen in the same colour over a long distance. Draw a ray diagram showing the dispersion through a prism when a narrow beam of white light is incident on one of its refracting surfaces. → When light enters obliquely from a denser medium to a rarer medium and the angle of incidence exceeds critical angle, the light reflects in the denser medium. Write in one word or at the most in one sentence about the following: accommodation. → Light should enter obliquely from a denser to a rarer medium. The eye resembles a - camera in many ways. The main parts of a human eye are: Sclera These droplets behave as glass prism. 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