Question 21. The human eye is the natural convex lens that refracts light. Structure of Eye. (ii) Stars near the horizon appear slightly higher than their actual position. Write about power of accommodation of human eye. 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. Answer: Given, that u = – 25 cm and y = –75 cm. Colour blindness is that defect of the eye due to which a person is unable to distinguish certain colours, sometimes even the primary colours. → Wavelength of red light is about 1.8 times to that of blue light. A person cannot see objects beyond 80 cm from his eye while a person with normal eyesight can see object easily placed upto 160 cm from the eye. Myopia (Short sightedness): It is a defect in which a person is unable to see far objects … Answer: Question 23. the focal length of the eye lens is too long, or. What do you understand by spectrum of white light? → Affected person can see far objects clearly but cannot see nearby objects clearly. 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. We are able to see the movie picture in a cinema hall. (b) (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. Spreading of light in various directions by colloid particles. 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. Thus, scattering of light makes the particles visible. Answer: → The air above hot surface becomes hot and rises. Answer: Explain, why a normal eye is not able to see distinctly the objects placed closer than 25 cm. The first prism splits the white light into its seven colour components. How does this happen? What is colour-blindness? Answer: ... With the help of ray diagram show: (i) the eye defect hypermetropia. Download free CBSE Sample paper for Class 10, Physics. The scattered blue light enters our eyes. Class 10 Science MCQs Chapter 11 Human Eye and Colourful World. → 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. → So, the light coming from a star near the horizon has to travel from rarer to denser medium and it bends towards the normal. What kind of retinal cells are lacking in person suffering from this defect? Question 6. (ii) most contracted state. 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. 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. → Such people require bifocal lens for correction. During sunset and sunrise, the sun is near horizon and therefore the sunlight has to travel larger distance in atmosphere. • Lens: It is composed of a fibrous, jelly like material. Solution : Convex lens. 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. (a) What kind of defect in vision is she suffering from? Extra Questions for Class 10 Science Chapter 11 Human Eye and Colourful World with Answers Solutions. To the observer O these rays appear to come from B which is above horizon. Eye defects. 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. This phenomenon is called dispersion. Answer: Question 9. Human Eye: working of human eye, Persistence of vision, Power of accommodation of human eye, Defects of vision. Here, tiny water droplets in the mist scatter light. What is hypermetropia (far-sightedness)? Give reason. → When light enters the rain drop, it first refracts and disperses. 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. A man with spectacles can read a book placed at 25 cm. 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. The focal length of the eye lens decreases. Answer: (a) What is myopia? Question 20. The near point of a normal human eye is at a distance of 25 centimetres from the eye. Millions of people of the developing countries are suffering from corneal blindness. The splitting of white light into its component colours is called dispersion of light. Use this phenomenon to explain why the clear sky appears blue or the sun appears reddish at sunrise. BOOK FREE CLASS; COMPETITIVE EXAMS. Therefore, the sky appears blue from the surface of the Earth. What type of defect of vision is he suffering from? 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. Why are ‘danger’ signal lights red in colour? What is astigmatism? But, when a person enters into a dimly lighted room, each iris takes some time to increase the diameter of the pupil, so that more amount of light can enter the eyes to see the object clearly and rod cells of the retina also take some time to adjust themselves to get the object in the dim light. The power of accommodation of the eye decreases with ageing. NCERT Exemplar for Class 10 Science Chapter 11 The Human Eye and The Colourful World Multiple Choice Questions 1. → Then it reflects internally and again refracts as it come out of the drop and the seven colours reach the eye of observer in form of rainbow. What is colour blindness? (ii) correction of hypermetropia by using a lens. Question 2. The ciliary muscles of a normal eye are in their State the functions of each of the following parts of the human eye: At sunrise and sunset when the sun is below the horizon, the light rays starting from sun are incident on these layers. Question 17. How does refraction of light take place in the atmosphere? The maximum accommodation of a normal eye is reached when the object is at a distance of 25 cm from the eyes. The Human Eye: It is a natural optical instrument which is used to see the objects by human beings. → Human eye: The sense organ that helps us to see. Seven colours of spectrum are violet, indigo, blue, green, yellow, orange and red also known as ‘VIBGYOR’. Why does it take some time to see objects in a dim room when you enter the room from bright sunlight outside? Due to gradual weakening of ciliary muscles and diminishing flexibility of the eye lens a certain defect of vision arises. Least deviated component: Red 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. The scattering of light by particles in its path is called Tyndall effect. Question 1. The type of questions that will be asked from NCERT Class 10 Science Unit 11 are displayed in the below provided NCERT Exemplar Class 10 Science Unit 11. Question 14. With the help of ciliary muscles the human eye can change its curvature and thus alter the focal length of its lens. → Since the physical conditions of the earth’s atmosphere are not constant the light from. Digital NCERT Books Class 10 Science pdf are always handy to use when you do not have access to physical copy. 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. (iii) Advanced sunrise and delayed sunset. Answer: b. (b) The ability of the eye lens to adjust its focal length is called automatic accommodation. The Human Eye and Its Structure ‘Human Eye’ is the organ of vision of the human body that enables us to see. Why is the colour of sky blue? What type of defect of vision is he suffering from? State the cause of dispersion of white light by a glass prism. The atmospheric refraction of light occurs in a medium of gradually changing refractive index. Question 18. How is presbyopia corrected? ... CBSE Previous Year Question Papers Class 10 Science; CBSE Previous Year Question Papers Class 12 Physics; CBSE Previous … State the two causes of myopia. A person cannot see distinctly objects kept beyond … Power of Accommodation of Human Eye: The human eye can clearly see a nearby object as well as an object on infinity. This is due to the ability of the eye lens to adjust its focal length which is known as accommodation. Describe with a ray diagram how this defect of vision can be … Human Eye and Colourful World. → Red is the least scattered colour. Defects of Vision in Eye (Myopia) Defects of Vision in Eye (Hypermetropia) Refraction of Light through a Glass Prism. → Light should enter obliquely from a denser to a rarer medium. He … The sun can be seen about two minutes before actual sunrise. → 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. Answer: Formation of Rainbow. Answer: A rainbow is a natural spectrum appearing in the sky Raindrop after a rain. 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. (i) If particles are very fine, they scatter mainly the blue colour of light (shorter wavelength). These particles are more effective in scattering of light of shorter wavelength mainly blue than larger wavelength. In the following diagram, the path of a ray of light passing through a glass prism is shown below. Question 10. Answer: A person can see clearly only up to 3 metres. What is meant by dispersion of white light? Dispersion of light concept is made understandable in a simple way. What causes astigmatism? 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. The least distance of distinct vision for a normal eye is (a) infinity (b) 25 cm (c) 2.5 cm (d) 25 m. Answer. Answer: 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. → A myopic person can see nearby objects clearly but cannot see distant objects clearly. NCERT Class 10 Science Unit 11 is for Human Eye and Colourful World. NCERT Books. 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. The ability of the human eye to continue to see the image of an object for very short duration even after the removal of that object is called persistence of vision. (i)  Apparent flickering of objects placed behind a hot object or fire. → The amount of light coming from stars also vary due to changing Refractive Index of atmosphere. NCERT Solutions for Class 10 Science Chapter 11: The Human Eye and Colourful World. Question 1. Explain why the image distance in the eye does not change when we change the distance of an object from the eye? However, the focal length of the eye lens cannot be decreased below a certain limit. All colours of light travel at the same speed in a vacuum. → Red is the least deviated colour as it has largest/longest wavelength. Answer: Image Formation by Concave Mirror. Answer: → Violet is the most deviated colour as it has smallest wavelength in visible spectrum. The defect of vision is myopia. (ii) correction of myopia using a lens. Studyrankers is a free educational platform for cbse k-12 students. Question 25. Thus, its focal length increases. Answer: This disease can be cured by replacing the defective cornea with the cornea of a donated eye. In fact the sensation produced by the image of an object lasts for nearly 1/16th of a second on retina. Solution: The difference of time is about 2 minutes each for early rise and late setting of the Sun. Atmospheric Refraction Effects. → The angle of incidence should exceed critical angle, the light reflects in the denser medium. (ii) Near point or 25 cm. Question 12. How will you use two identical prisms so that a narrow beam of white light incident on one prism emerges out of the second prism as white light? → The near-point of the old person having presbyopia gradually recedes and becomes much more than 25 cm away. Answer: A rainbow is a natural spectrum appearing in the sky … Question 1. Extra Questions for Class 10 Science Chapter 11 Human Eye and Colourful World with Answers Solutions. 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. A person is advised to wear spectacles with concave lenses. When we look at the sky, the scattered light enters our eyes which majorly contains blue, colour and hence the sky appears blue. For an astronaut, the sky would appear dark because in space there is no atmosphere to scatter light. The water droplets act like small prisms. The + sign with for the power indicates a convergent lens. This defect is then corrected by using bi-focal lenses of suitable focal lengths. CBSE Class 10 Science Notes Chapter 11 Human Eye and Colourful World. (b) Curvature increrases. A concave lens of focal length 4 m should be used. → It results in fluctuation in apparent position of object. When a monochromatic light having only one wavelength, passes through a prism, will it show dispersion? Answer: Question 24. What is Tyndall effect? So, it is important to know the defects of vision and which type of lens can cure which defect. Hence shorter waves are scattered .. away and longer (red) waves reach our eye. Answer: The layers of air nearer to earth are denser than those above it. The band of the coloured components formed due to dispersion of white light is called ‘spectrum’. Explain giving a reason why the sky appears blue to an observer from the surface of the Earth. The eye lens becomes thicker. What causes presbyopia? Explain with an example. Answer: This wavering of light is an effect of atmospheric refraction. Lakhmir Singh Physics Class 10 Solutions The Human Eyes And The Colorful World. 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 enables us to see nearby objects clearly. A student is observing the diagram showing the path of a ray of light passing through a glass prism. It arises due to the gradual weakening of the ciliary muscles and diminishing flexibility of the eye lens. So he can see the objects clearly only in one plane. → So rays bend towards the normal. It is due to persistence of vision that we are able to see movie pictures in a cinema hall. Answer: 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. Question 16. Since there are no particle in space, the sky appear dark to astronauts. State one role of ciliary muscles in the human eye. When sunlight passes through the atmosphere, the fine particles in air scatter the blue colour more strongly than red. Write in one word or at the most in one sentence about the following: The sun can be seen about two minutes before actual sunrise because of atmospheric refraction. Solution: These droplets behave as glass prism. This enables us to see distant objects clearly. (b) What is the focal length of the corrective lens? → Issac Newton was the first person who proved that sunlight is made up of seven colours : (i)  He passed sunlight through a glass prism to form a band of seven colours. → 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. Name the type of lens required by such persons to improve the vision. State the objectives of organising such campaigns in schools. This is possible only when you have the best CBSE Class 10 Science study material and a smart preparation plan. (ii) He tried to split the colours further by putting another prism ahead of the prism forming spectrum but he failed to obtain more colours. Refraction of Light through a Rectangular Glass Slab. Answer: Explore the structure of the ear and its functions only at BYJU’S. It is also called eyesight. Curvature decreases. Question 5. The far point of a normal human eye is at infinity. This ability of the human eye is called the power of accommodation of human eye. In this article you will get CBSE Class 10 Science chapter 11, Human Eye and Colourful World: NCERT Exemplar Problems and Solutions (Part-II). (iii) Pupil Each human eye sizes for approximately 2.5 cm in diameter. Explains the various defects that happen for human and also describes the ways to correct it. The ability to see is called vision. ... 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. → Use of convex lens of suitable power can correct the defect. (ii) The smallest distance, at which the eye can see objects clearly without strain. 1. Answer: Question 2. Focal length increases. 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. NCERT Solutions for Class 10 explains the detailed structure of the human eye. Human Eye and Colourful World Extra Questions Very Short Answer Type. Question 9. In this page, you can find CBSE Class 10 Science Chapter 11 Extra Questions and Answers Human Eye and Colourful World Pdf free download, NCERT Extra Questions for Class 10 Science will make your practice complete. Such a person may suffer from myopia and hypermetropia. lamge distance in the eye is the distance between the eye lens and the retina and it is fixed. When we are looking at objects closer to the eye, the ciliary muscles contract. This is because focal length of the lens of a normal human eye cannot be decreased below certain limit i.e., 25 cm. What is the cause of dispersion? It is produced by dispersion of sunlight by tiny water droplets, present in the atmosphere. Question 3. without putting any strain on the eye. → The refractive index of earth’s atmosphere in general increases from top to bottom. 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. 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. Objectives of organising such campaigns: Question 2. Cataract can be cured by eye surgery. Solution: This is due to. The defect of the eye due to which a person is unable to distinguish between certain colours, is known as colour blindness. Answer: However, there is lateral displacement. This defect can be corrected by using cylindrical lenses of suitable focal length and suitable axis in the spectacles. Human Eye and Colourful World class 10 Notes. Question 8. (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. Answer: (a) Lens becomes thin Or Get class 10 study materials at BYJU'S. Causes of hypermetropia: This defect arises because either: Hypermetropia can be corrected by using convex lens of suitable focal length in spectacles. Explain the structure and function of such a lens. This increases the curvature of the eye lens. THE HUMAN EYE & Colourful world. Answer: (c) Concave lens. So, the sky appears blue. How can you along with your classmates contribute in this noble cause? Question 7. Defects of vision and their correction. Save my name, email, and website in this browser for the next time I comment. The nearest point up to which the eye can see an object clearly without any strain, is called the near point of the eye. This reduces the vision in old age. It is like a camera which has a lens and screen system. This defect is mainly due to the cornea that is not perfectly spherical. The main parts of a human eye are: Sclera → While sunset and sunrise, the colour of the sun and its surrounding appear red. How did Newton, using two identical glass prisms, show that white light is made of seven colours? Find the nature, the focal length and the power of the correcting lens. → When the sun is below horizon, the rays have to pass from rarer to denser medium. Why there is no dispersion of light refracted through a rectangular glass slab? Question 4. Find the nature, the focal length and the power of the correcting lens used for the defective vision. Class 1 - 3; Class 4 - 5; Class 6 - 10; Class 11 - 12; CBSE. This defect of the eye is hypermetropia. What are the essential parts of the eye and their functions Name the component of white light that deviates the least and the component that deviates the most while passing through a glass prism. Hence sun appears red. Candidates who are ambitious to qualify the Class 10 with good score can check this article for Notes. → Clouds are formed by water vapours. What do you mean by power of accommodation of an eye? Why do different rays deviate differently in the prism? (i) Mirrors used by dentists to examine teeth. It will only show deviation. Question 3. A rainbow is always formed in the direction opposite to that of the sun. Name the various colours of spectrum of white light in proper sequence. Answer: : Question 4. Or When these enter a transparent substance like prism, all slow down by different amounts depending on their wavelength. Prescribe a lens for spectacles so that he can see clearly up to 12 metres. Danger signal lights are red in colour because the red coloured light having longer wavelength is scattered the least by fog or smoke. Question and Answer forum for K12 Students. For most people, the near point gradually recedes and the far point comes closer. Question 2. Answer: The revision notes covers all important formulas and concepts given in the chapter. (i) Concave mirror Class 10 Class 12. A person is advised to wear spectacles with convex lenses. With the help of labelled ray diagrams show (iii) Even larger particles scatter all the colours of light that is why it appears white. Cornea: Refraction of the light rays falling on the eye. To assist you with that, we are here … Download free PDF of best NCERT Solutions , Class 10, Physics, CBSE- Human Eye and the Colourful World . accommodation. A collection of questions on CBSE- Human Eye and the Colourful World with solutions created by best teachers are available as a PDF … → The upper layer of atmosphere contains very fine particles of water vapours and gases. The tiny dust particles present in the air of room scatter the beam of light all around the room. 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.

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