Solution: BOOK FREE CLASS; COMPETITIVE EXAMS. → It enhances the ability to detect faint objects. The Human Eye and Its Structure ‘Human Eye’ is the organ of vision of the human body that enables us to see. They pass through successively denser layers and thus get bent more and more towards the normal until they fall upon the eye of the observer O. Question 1. Class 10 Science MCQs Chapter 11 Human Eye and Colourful World. → Since the physical conditions of the earth’s atmosphere are not constant the light from. → Both these effects are responsible for twinkling of stars. As a result the sun appears higher than its actual position. A person is advised to wear spectacles with convex lenses. What is the cause of dispersion? → When the sun is below horizon, the rays have to pass from rarer to denser medium. Question 21. The least distance of distinct vision for a normal eye is (a) infinity (b) 25 cm (c) 2.5 cm (d) 25 m. Answer. State the two causes of myopia. Question 5. Question 1. (i)  Apparent flickering of objects placed behind a hot object or fire. (iii) Even larger particles scatter all the colours of light that is why it appears white. without putting any strain on the eye. How does atmospheric refraction affect sunrise and sunset? Cataract can be cured by eye surgery. → Diameter of eye ball – 2.3 cm. A collection of questions on CBSE- Human Eye and the Colourful World with solutions created by best teachers are available as a PDF … presbyopia. The splitting of white light into its component colours is called dispersion of light. You can also get free sample papers, Notes, Important Questions. Answer: → The air above hot surface becomes hot and rises. Answer: 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. When sunlight passes through the atmosphere, the fine particles in air scatter the blue colour more strongly than red. Therefore, the sky appears blue from the surface of the Earth. → So, the light coming from a star near the horizon has to travel from rarer to denser medium and it bends towards the normal. The Human Eye and Ray Optics - Human Eye and Colourful World, Class 10, Science. Objectives of organising such campaigns: Question 2. (ii) Near point or 25 cm. (i) Path of light becomes visible when light enters a dark and dusty room through a slit or ventilator. • Lens: It is composed of a fibrous, jelly like material. To understand social issues and problems. When a ray of light falls on water drop (or raindrop) it undergoes refraction and dispersion to form a spectrum. In this diagram, the angle of incidence, the angle of emergence and the angle of … 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. 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. A rainbow is always formed in the direction opposite to that of the sun. Colour blindness is that defect of the eye due to which a person is unable to distinguish certain colours, sometimes even the primary colours. The Human Eye: It is a natural optical instrument which is used to see the objects by human beings. A person can see clearly only up to 3 metres. Human Eye: working of human eye, Persistence of vision, Power of accommodation of human eye, Defects of vision. (a) Lens becomes thin → The near-point of the old person having presbyopia gradually recedes and becomes much more than 25 cm away. (a) Myopia Describe with a ray diagram how this defect of vision can be corrected by using spectacles. Question 9. 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The fine particles in the atmosphere scatter light of shorter wavelength (blue colour) more strongly than the light of longer wavelength (red colour). Answer: Answer: Answer: 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. The ciliary muscles of a normal eye are in their → When light enters the rain drop, it first refracts and disperses. The pictures in the form of a long film are projected on the screen at a rate of about 24 pictures per second. A person cannot see distinctly objects kept beyond … To the observer O these rays appear to come from B which is above horizon. Class 1 - 3; Class 4 - 5; Class 6 - 10; Class 11 - 12; CBSE. Explain the reason why stars appear to twinkle and the planets do not twinkle. Water vapours condense to form water droplets due to larger size of droplets, all colours of light are scattered and clouds appear white. Answer: Malfunctions of Eyes: Cataract: In old age the cornea becomes cloudy. (b)Why is the normal eye unable to focus on an object placed within 10 cm from the eye? Solution: Answer: Answer: → The amount of light coming from stars also vary due to changing Refractive Index of atmosphere. Thus, its focal length increases. The light of shorter wavelength (blue) of the visible spectrum is scattered more than the light of longer wavelength by the atmospheric particles. ... With the help of ray diagram show: (i) the eye defect hypermetropia. The first prism splits the white light into its seven colour components. For an astronaut, the sky would appear dark because in space there is no atmosphere to scatter light. Answer: → While sunset and sunrise, the colour of the sun and its surrounding appear red. The name of the defect is Presbyopia. Function of Ear. State its cause. (a) What is myopia? (ii) correction of myopia using a lens. Question 8. ... CBSE Previous Year Question Papers Class 10 Science; CBSE Previous Year Question Papers Class 12 Physics; CBSE Previous … Question 9. (ii) Iris Science NCERT Grade 10, Chapter 11, Human Eye and Colourful World lays emphasis on the understanding of the working of the human eye along with the functions of different parts of the human eye. 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. Write about power of accommodation of human eye. Draw a ray diagram showing the dispersion through a prism when a narrow beam … What should the appearance of the sky be during the day for an astronaut staying in the international space station orbiting the Earth? 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. With the help of labelled ray diagrams show The sun can be seen about two minutes before actual sunrise. : The second prism can be considered to be placed in an inverted position with respect to the first. Given: = -25 cm. Why does the sky appear dark to astronauts? → Sometimes a person may suffer from both myopia and hypermetropia. State the cause of dispersion of white light by a glass prism. 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. Question 6. When a beam of light enters a smoke-filled dark room through a small hole, then its path becomes visible to us. Human Eye and Colourful World - Know the working of a human eye, the difference between Cornea and Retina. Or The sun can be seen about two minutes before actual sunrise because of atmospheric refraction. 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. (c) What is the nature of the corrective lens? Near point or Least distance of distinct vision, Advantage of the eyes in front of the face. Question 18. This is due to. → Clouds are formed by water vapours. (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. Dispersion of light concept is made understandable in a simple way. If you have any queries regarding Human Eye and Colourful World … Answer: At sunrise and sunset when the sun is below the horizon, the light rays starting from sun are incident on these layers. Since there are no particle in space, the sky appear dark to astronauts. These particles are more effective in scattering of light of shorter wavelength mainly blue than larger wavelength. (iii) He formed a spectrum from sunlight and placed an identical but inverted prism in front of prism forming the spectrum. Seven colours of spectrum are violet, indigo, blue, green, yellow, orange and red also known as ‘VIBGYOR’. The revision notes covers all important formulas and concepts given in the chapter. This increases the curvature of the eye lens. Focal length decreases. As a result, the cornea has different curvatures in different directions of the horizontal and vertical planes. → A myopic person can see nearby objects clearly but cannot see distant objects clearly. Answer: The phenomenon in which a part of the light incident on a particle is redirected in different directions is called the scattering of light. This disease can be cured by replacing the defective cornea with the cornea of a donated eye. Answer: → It is the defect of vision due to which an old person cannot see the nearby objects clearly due to loss of power of accomodation of the eye. This defect is mainly due to the cornea that is not perfectly spherical. Question 16. The eye lens becomes thicker. Question 3. So, danger signs are made in red colour. This defect is called presbyopia. 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 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. Extra Questions for Class 10 Science Chapter 11 Human Eye and Colourful World with Answers Solutions. All the seven colours combined by the inverted prism and emerged as white light. For scattering of light, particles are required. → Red is the least scattered colour. What is colour blindness? → The upper layer of atmosphere contains very fine particles of water vapours and gases. 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. After the dispersion of light and internal reflections, the band of colours reaches observer’s eye in the form of a rainbow. Question 24. Image Formation by Concave Mirror. Ability of the eye lens to focus nearby as well as distant objects on the retina by changing the curvature or focal length of the eye lens is known as power of accommodation. … Question 15. NCERT Books. He … 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. Write two causes for development of this defect. Since the atmosphere consists of varying densities the apparent position of the object, as seen through the hot air fluctuates. This defect of the eye is hypermetropia. Thus, scattering of light makes the particles visible. So, it is important to know the defects of vision and which type of lens can cure which defect. The band of the coloured components formed due to dispersion of white light is called ‘spectrum’. When these enter a transparent substance like prism, all slow down by different amounts depending on their wavelength. → Violet is the most deviated colour as it has smallest wavelength in visible spectrum. Question 7. The colour blind persons do not possess cone cells that respond to certain colours. 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. (c) Concave lens. It is also called eyesight. NCERT Exemplar for Class 10 Science Chapter 11 The Human Eye and The Colourful World Multiple Choice Questions 1. Here, tiny water droplets in the mist scatter light. Human Eye and Colourful World class 10 Notes. It is like a camera which has a lens and screen system. (iv) Retina 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. (CBSE 2009) Answer: (a) Hypermetropia: It is also called long-sightedness. Download free CBSE Sample paper for Class 10, Physics. What is colour-blindness? When the cilary muscles are relaxed, the lens becoems thin. NCERT Solutions for Class 10 Science Chapter 11: The Human Eye and Colourful World. Question 4. lamge distance in the eye is the distance between the eye lens and the retina and it is fixed. All the NCERT exemplar solutions are framed in a systematic manner according to the latest CBSE class 10 science syllabus (2020-21). This is due to the ability of the eye lens to adjust its focal length which is known as accommodation. (b) A glass slab acts as a combination of two identical glass prisms. 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. Explain giving a reason why the sky appears blue to an observer from the surface of the Earth. What is meant by ‘persistence of vision’? Question 12. The tiny dust particles present in the air of room scatter the beam of light all around the room. So, the sky appears blue. Question 8. Question 4. 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. During this, most of the shorter wavelengths present in it are scattered away from our line of sight by the molecules of air and other fine particles in the atmosphere. Astigmatism. With the help of ciliary muscles the human eye can change its curvature and thus alter the focal length of its lens. Question 2. All colours of light travel at the same speed in a vacuum. (b) Answer: Extra Questions for Class 10 Science Chapter 11 Human Eye and Colourful World with Answers Solutions. 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. Name the type of lens required by such persons to improve the vision. → Human eye: The sense organ that helps us to see. How is astigmatism corrected? It is due to persistence of vision that we are able to see movie pictures in a cinema hall. THE HUMAN EYE & Colourful world. The band of seven colours formed on white screen when a beam of white light (or sunlight) is passed through a glass prism is called spectrum of white light. During sunset and sunrise, the sun is near horizon and therefore the sunlight has to travel larger distance in atmosphere. Answer: Question 4. Parts of Human Eye • Cornea: It is the outermost, transparent part. State the functions of each of the following parts of the human eye: What is meant by advance sunrise and delayed sunset. The defect of the vision is hypermetropia. This reduces the vision in old age. Draw a labelled diagram to explain. → It results in fluctuation in apparent position of object. How are we able to see nearby and also the distant objects clearly? → Focal length of the eye lens becomes too long. The human ear is an important organ of the human body responsible for hearing and balance. → The star appears bright when more light from star reaches our eyes and the same star appears dull when less amount of light reaches our eyes. The near point of a normal human eye is at a distance of 25 centimetres from the eye. Explain why the image distance in the eye does not change when we change the distance of an object from the eye? 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. Also indicate the order of the … The layers of air nearer to earth are denser than those above it. Human Eye Diagram class 10 | How to Draw Human Eye Diagram … Studyrankers is a free educational platform for cbse k-12 students. Cone-shaped retinal cells are responsible for making a person differentiate between colours. Due to gradual weakening of ciliary muscles and diminishing flexibility of the eye lens a certain defect of vision arises. When these colour components fall on the second prism, it recombines them to form white light. Such a person may suffer from myopia and hypermetropia. The maximum accommodation of a normal eye is reached when the object is at a distance of 25 cm from the eyes. (ii) most contracted state. How can you along with your classmates contribute in this noble cause? → This results in fluctuation of apparent position of star. State reason to justify your answer. → So rays bend towards the normal. As these slow down by different amounts, different colours are refracted through different angles which causes dispersion. State one role of ciliary muscles in the human eye. As rays of all colours emerge in the same direction, i.e., the direction of the incidence of white light, there is no dispersion. BNAT; Classes. Answer: The space is occupied by cool air. The atmospheric refraction of light occurs in a medium of gradually changing refractive index. So he can see the objects clearly only in one plane. Question 14. (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 and Answer forum for K12 Students. It has "nearly a spherical shape. This is called internal reflection. State the changes that occur in the curvature and focal length of the eye lens while viewing (a) a distance object, (b) nearby objects. The twinkling of a star is due to atmospheric refraction of starlight. How does refraction of light take place in the atmosphere? 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. What is meant by dispersion of white light? Answer: Least deviated component: Red Answer: The human eye structure and function makes it easy to distinguish the objects based on colour, size and other parameters. Millions of people of the developing countries are suffering from corneal blindness. Question 11. Answer: 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. (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. Why are ‘danger’ signal lights red in colour? Power of Accommodation of Human Eye: The human eye can clearly see a nearby object as well as an object on infinity. Explain, why a normal eye is not able to see distinctly the objects placed closer than 25 cm. Defects of Vision in Eye (Myopia) Defects of Vision in Eye (Hypermetropia) Refraction of Light through a Glass Prism. Question 20. Our eye is the most important natural optical instrument. We are able to see the movie picture in a cinema hall. due to decrease in the focal length of the eye lens. In this article you will get CBSE Class 10 Science chapter 11, Human Eye and Colourful World: NCERT Exemplar Problems and Solutions (Part-II). → Due to changing Refractive Index (RI) of medium, the light appears to come from different directions. 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