Explain why it is so. Question 2. → Light should enter obliquely from a denser to a rarer medium. Question 4. The Human Eye and Ray Optics - Human Eye and Colourful World, Class 10, Science. At sunrise and sunset when the sun is below the horizon, the light rays starting from sun are incident on these layers. → The amount of light coming from stars also vary due to changing Refractive Index of atmosphere. This increases the curvature of the eye lens. (b)Why is the normal eye unable to focus on an object placed within 10 cm from the eye? Write about power of accommodation of human eye. A person needs a lens of power -4.5 D for correction of her vision. A person cannot see distinctly objects kept beyond … Near point or Least distance of distinct vision, Advantage of the eyes in front of the face. It arises due to the gradual weakening of the ciliary muscles and diminishing flexibility of the eye lens. 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. The first prism splits the white light into its seven colour components. Thus, the normal eye is unable to focus an object placed within 10 cm from the eye because it is beyond its power of accommodation. presbyopia. A rainbow is always formed in the direction opposite to that of the sun. → 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. Explain the reason why stars appear to twinkle and the planets do not twinkle. What are the essential parts of the eye and their functions Answer: Answer: → When light enters the rain drop, it first refracts and disperses. (i) Concave mirror The defect of the vision is hypermetropia. He … Question 16. → Diameter of eye ball – 2.3 cm. Here, v= -3 m, u = -12 m, f = ? This spectrum undegoes internal reflection (inside the raindrop) and finally refracted again when it comes out of the raindrop. 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. Question 9. 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. 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. What is meant by ‘persistence of vision’? The fine particles in the atmosphere scatter light of shorter wavelength (blue colour) more strongly than the light of longer wavelength (red colour). Write the name of this defect. Answer: It is like a camera which has a lens and screen system. However, the focal length of the eye lens cannot be decreased below a certain limit. CBSE Class 10 Science Notes Chapter 11 Human Eye and Colourful World. The nearest point up to which the eye can see an object clearly without any strain, is called the near point of the eye. Give reason. What is astigmatism? This defect is then corrected by using bi-focal lenses of suitable focal lengths. Question 19. What is hypermetropia (far-sightedness)? Name the various colours of spectrum of white light in proper sequence. 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. In most relaxed state. The human eye can focus objects at different distances by adjusting the focal length of the eye lens. (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. What is presbyopia? ... CBSE Previous Year Question Papers Class 10 Science; CBSE Previous Year Question Papers Class 12 Physics; CBSE Previous … → Since the physical conditions of the earth’s atmosphere are not constant the light from. As a result, the cornea has different curvatures in different directions of the horizontal and vertical planes. When a ray of light falls on water drop (or raindrop) it undergoes refraction and dispersion to form a spectrum. A rainbow is a natural spectrum appearing in the sky Raindrop after a rain. Question 18. 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. → Use of convex lens of suitable power can correct the defect. Focal length increases. The phenomenon in which a part of the light incident on a particle is redirected in different directions is called the scattering of light. With the help of labelled ray diagrams show The twinkling of a star is due to atmospheric refraction of starlight. Defects of Vision in Eye (Myopia) Defects of Vision in Eye (Hypermetropia) Refraction of Light through a Glass Prism. (b) The ability of the eye lens to adjust its focal length is called automatic accommodation. 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. Answer: (i) If particles are very fine, they scatter mainly the blue colour of light (shorter wavelength). (ii) most contracted state. Answer: Dispersion of White Light by Glass Prism. Explain, why a normal eye is not able to see distinctly the objects placed closer than 25 cm. The pictures in the form of a long film are projected on the screen at a rate of about 24 pictures per second. Human Eye and Colourful World class 10 Notes. (b) Curvature increrases. The difference of time is about 2 minutes each for early rise and late setting of the Sun. The human ear is an important organ of the human body responsible for hearing and balance. 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. Lakhmir Singh Physics Class 10 Solutions The Human Eyes And The Colorful World. → It is done by using concave lens of appropriate power. Draw a ray diagram showing the dispersion through a prism when a narrow beam … 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. If you have any queries regarding Human Eye and Colourful World … The scattering of light by particles in its path is called Tyndall effect. 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. Question 3. This defect of the eye is hypermetropia. Question 1. In which of the two cases is the focal length of the eye-lens more? A Glimpse of CBSE Class 10 Science Marking Scheme NCERT Exemplar Class 10 Science Unit 11 Human Eye and Colourful World. This defect is called presbyopia. The ability to see is called vision. Download free PDF of best NCERT Solutions , Class 10, Physics, CBSE- Human Eye and the Colourful World . Why there is no dispersion of light refracted through a rectangular glass slab? During sunset and sunrise, the sun is near horizon and therefore the sunlight has to travel larger distance in atmosphere. What causes presbyopia? A concave lens of focal length 4 m should be used. The eye resembles a - camera in many ways. Answer: The person with … A person is advised to wear spectacles with concave lenses. Water vapours condense to form water droplets due to larger size of droplets, all colours of light are scattered and clouds appear white. Far-sightedness/Long-sightedness/Hypermetropia. … without putting any strain on the eye. This is due to. (iii) Even larger particles scatter all the colours of light that is why it appears white. (ii) Medium sized particles scatter mainly the red colour (longer wavelength). State the two causes of myopia. When we look at the sky, the scattered light enters our eyes which majorly contains blue, colour and hence the sky appears blue. The blue colour of the sky is due to the scattering of sunlight by the molecules of the atmosphere. How can you along with your classmates contribute in this noble cause? 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. → So, the light coming from a star near the horizon has to travel from rarer to denser medium and it bends towards the normal. Answer: Therefore, it can be seen clearly from a distance. (i) Path of light becomes visible when light enters a dark and dusty room through a slit or ventilator. → Due to changing Refractive Index (RI) of medium, the light appears to come from different directions. 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. 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. The second prism can be considered to be placed in an inverted position with respect to the first. The far point of a normal human eye is at infinity. 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: Answer: → Sometimes a person may suffer from both myopia and hypermetropia. → Located in eye sockets in skull. All the NCERT exemplar solutions are framed in a systematic manner according to the latest CBSE class 10 science syllabus (2020-21). Explain giving a reason why the sky appears blue to an observer from the surface of the Earth. 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. Tyndall effect can also be observed when sunlight passes through a canopy of a dense forest. → The refractive index of earth’s atmosphere in general increases from top to bottom. When we are looking at objects closer to the eye, the ciliary muscles contract. Find the nature, the focal length and the power of the correcting lens. 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. Solution: Question 1. (i) most relaxed → The near-point of the old person having presbyopia gradually recedes and becomes much more than 25 cm away. It has "nearly a spherical shape. Since the atmosphere consists of varying densities the apparent position of the object, as seen through the hot air fluctuates. → Focal length of the eye lens becomes too long. 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? Solution: Answer: 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 8. The maximum accommodation of a normal eye is reached when the object is at a distance of 25 cm from the eyes. The power of accommodation of the eye decreases with ageing. As a result the sun appears higher than its actual position. All NCERT textbook questions have been solved by our expert teachers. → Clouds are formed by water vapours. Explains the various defects that happen for human and also describes the ways to correct it. Here, tiny water droplets in the mist scatter light. Answer: → So rays bend towards the normal. This reduces the vision in old age. The focal length of the eye lens decreases. Answer: → 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. To understand social issues and problems. (b) A glass slab acts as a combination of two identical glass prisms. 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. Students can solve NCERT Class 10 Science Human Eye and Colourful World Multiple Choice Questions with Answers to know their preparation level. It is due to persistence of vision that we are able to see movie pictures in a cinema hall. 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. NCERT Books. Atmospheric Refraction Effects. Answer: It is produced by dispersion of sunlight by tiny water droplets, present in the atmosphere. Human Eye Diagram class 10 | How to Draw Human Eye Diagram … Answer: Since we see the blue light from everywhere overhead, the sky appears blue. (a) Lens becomes thin Draw a labelled diagram to explain. → Due to this most of the blue light (shorter wavelength) are scattered away by the particles. What type of defect of vision is he suffering from? Thus, scattering of light makes the particles visible. Answer: Question 2. A person can see clearly only up to 3 metres. Thus, its focal length increases. What do you mean by power of accommodation of an eye? Answer: b. Question 1. (i) Apparent flickering of objects placed behind a hot object or fire. → 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. 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. For an astronaut, the sky would appear dark because in space there is no atmosphere to scatter light. Answer: The light of shorter wavelength (blue) of the visible spectrum is scattered more than the light of longer wavelength by the atmospheric particles. Following are the important function of the ear: Hearing. (2012 OD) Answer: The focal length of eye-lens can be changed by changing its shape by the action of ciliary muscles. (c) Concave lens. Describe with a ray diagram how this defect of vision can be corrected by using spectacles. It is least scattered by fog and smoke and can be seen in the same colour over a long distance. Eye defects. Question 22. What is meant by scattering of light? 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 a monochromatic light having only one wavelength, passes through a prism, will it show dispersion? Answer: Question 3. The lens used in the spectacles has power – 2.0 D. The man without spectacles can read the book placed at which distance? Question 10. The name of the defect is Presbyopia. Cataract can be cured by eye surgery. Colour blindness is that defect of the eye due to which a person is unable to distinguish certain colours, sometimes even the primary colours. → When the sun is below horizon, the rays have to pass from rarer to denser medium. : Tamilnadu Board Class 10 English Solutions, Tamilnadu Board Class 9 Science Solutions, Tamilnadu Board Class 9 Social Science Solutions, Tamilnadu Board Class 9 English Solutions, Light Reflection and Refraction Class 10 Extra Questions with Answers Science Chapter 10, Electricity Class 10 Extra Questions with Answers Science Chapter 12, MCQ Questions for Class 10 Social Science SST with Answers PDF Download Chapter Wise, MCQ Questions for Class 9 Science with Answers PDF Download Chapter Wise, MCQ Questions with Answers for Class 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, and 1 all Subjects, MCQ Questions for Class 11 Economics with Answers Chapter Wise PDF Download, MCQ Questions for Class 11 Accountancy with Answers PDF Download Chapter Wise, MCQ Questions for Class 12 Economics with Answers Chapter Wise PDF Download, MCQ Questions for Class 11 Biology with Answers Chapter Wise PDF Download, MCQ Questions for Class 11 Chemistry with Answers Chapter Wise PDF Download, MCQ Questions for Class 11 Physics with Answers Chapter Wise PDF Download, MCQ Questions for Class 11 Maths with Answers Chapter Wise PDF Download. → 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. Near-sightedness/Short-sightedness/Myopia. Each human eye sizes for approximately 2.5 cm in diameter. Explain the structure and function of such a lens. So, it is important to know the defects of vision and which type of lens can cure which defect. How did Newton, using two identical glass prisms, show that white light is made of seven colours? As rays of all colours emerge in the same direction, i.e., the direction of the incidence of white light, there is no dispersion. Formation of Rainbow. Since there are no particle in space, the sky appear dark to astronauts. Due to gradual weakening of ciliary muscles and diminishing flexibility of the eye lens a certain defect of vision arises. A detailed explanation of the human eye along with its structural representation covering the important parts is mentioned in the chapter. Pupil: To regulate and control the amount of light entering the eye. The defect of the eye due to which a person is unable to distinguish between certain colours, is known as colour blindness. The planets are much closer to the earth and are thus seen as extended sources. Answer: Answer: After the dispersion of light and internal reflections, the band of colours reaches observer’s eye in the form of a rainbow. (ii) Stars near the horizon appear slightly higher than their actual position. ... 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. BNAT; Classes. (iv) Retina To assist you with that, we are here … It will only show deviation. In fact the sensation produced by the image of an object lasts for nearly 1/16th of a second on retina. (ii) correction of myopia using a lens. Why is the colour of sky blue? CBSE Class-10 Revision Notes and Key Points. Explain with an example. (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. Why do different rays deviate differently in the prism? Answer: 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. How does atmospheric refraction affect sunrise and sunset? This defect can be corrected by using cylindrical lenses of suitable focal length and suitable axis in the spectacles. The tiny dust particles present in the air of room scatter the beam of light all around the room. Answer: Question 17. Seven colours of spectrum are violet, indigo, blue, green, yellow, orange and red also known as ‘VIBGYOR’. Describe the formation of rainbow in the sky with the help of a diagram. Answer: In this defect, a person cannot focus on both horizontal as well as vertical lines at the same time. (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. Extra Questions for Class 10 Science Chapter 11 Human Eye and Colourful World with Answers Solutions. → Affected person can see far objects clearly but cannot see nearby objects clearly. Draw a ray diagram to show the dispersion of white light by a glass prism. Or ... With the help of ray diagram show: (i) the eye defect hypermetropia. → 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. Download free CBSE Sample paper for Class 10, Physics. After refraction at two parallel faces of a glass slab, a ray of light emerges in a direction parallel to the direction of incidence of white light. Malfunctions of Eyes: Cataract: In old age the cornea becomes cloudy. Question 7. → Human eye: The sense organ that helps us to see. Question 1. Focal length decreases. → It results in fluctuation in apparent position of object. stars appears to come from different directions. Also indicate the order of the … Structure of Eye. Lakhmir Singh Physics Class 10 Solutions Page No:269. Extra Questions for Class 10 Science Chapter 11 Human Eye and Colourful World with Answers Solutions. (ii) Iris Class 10 Class 12. What causes astigmatism? (b) What is the focal length of the corrective lens? It provides most of the refraction of light. THE HUMAN EYE & Colourful world. Question 7. → Such people require bifocal lens for correction. 1. Answer: This enables us to see nearby objects clearly. For scattering of light, particles are required. The colour blind persons do not possess cone cells that respond to certain colours. → Red is the least deviated colour as it has largest/longest wavelength. Hence shorter waves are scattered .. away and longer (red) waves reach our eye. lamge distance in the eye is the distance between the eye lens and the retina and it is fixed. Explain why the image distance in the eye does not change when we change the distance of an object from the eye? (iii) Pupil → This results in fluctuation of apparent position of star. State the functions of each of the following parts of the human eye: Question 13. 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. State the cause of dispersion of white light by a glass prism. To the observer O these rays appear to come from B which is above horizon. About 1.8 times to that of the object is at a distance distinct... Check this article for Notes with … CBSE Class-10 Revision Notes and Key Points second prism be. 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