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. At sunrise and sunset when the sun is below the horizon, the light rays starting from sun are incident on these layers. Explain giving a reason why the sky appears blue to an observer from the surface of the Earth. State the objectives of organising such campaigns in schools. NCERT Exemplar for Class 10 Science Chapter 11 The Human Eye and The Colourful World Multiple Choice Questions 1. Millions of people of the developing countries are suffering from corneal blindness. 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. Answer: These droplets behave as glass prism. ... CBSE Previous Year Question Papers Class 10 Science; CBSE Previous Year Question Papers Class 12 Physics; CBSE Previous … due to decrease in the focal length of the eye 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. The eye resembles a - camera in many ways. The water droplets act like small prisms. (b)Why is the normal eye unable to focus on an object placed within 10 cm from the eye? In most relaxed state. 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. (ii) most contracted state. Write two causes for development of this defect. The splitting of white light into its component colours is called dispersion of light. If you have any queries regarding Human Eye and Colourful World … Answer: Answer: Answer: The light of shorter wavelength (blue) of the visible spectrum is scattered more than the light of longer wavelength by the atmospheric particles. The defect of the vision is hypermetropia. This phenomenon is called dispersion. All colours of light travel at the same speed in a vacuum. Question 1. As a result the sun appears higher than its actual position. Explain why the image distance in the eye does not change when we change the distance of an object from the eye? Answer: It is least scattered by fog and smoke and can be seen in the same colour over a long distance. 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. A concave lens of focal length 4 m should be used. Question 2. Solution: Student sitting at the back bench in a class is not able to see what is written on the blackboard. (b) A glass slab acts as a combination of two identical glass prisms. What is astigmatism? Astigmatism. The least distance of distinct vision for a normal eye is (a) infinity (b) 25 cm (c) 2.5 cm (d) 25 m. Answer. What is meant by scattering of light? It has "nearly a spherical shape. Refraction of Light through a Rectangular Glass Slab. Question 16. Parts of Human Eye • Cornea: It is the outermost, transparent part. 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. Answer: The fine particles in the atmosphere scatter light of shorter wavelength (blue colour) more strongly than the light of longer wavelength (red colour). presbyopia. 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. This enables us to see distant objects clearly. Answer: Human Eye and Colourful World class 10 Notes. accommodation. ... 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. Formation of Rainbow. State the functions of each of the following parts of the human eye: → Clouds are formed by water vapours. 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. 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. Hence sun appears red. In the following diagram, the path of a ray of light passing through a glass prism is shown below. → So rays bend towards the normal. → It is done by using concave lens of appropriate power. Tyndall effect can also be observed when sunlight passes through a canopy of a dense forest. Question 10. How does refraction of light take place in the atmosphere? Class 10 Science MCQs Chapter 11 Human Eye and Colourful World. Bifocal lens is required to improve the vision. (b) The ability of the eye lens to adjust its focal length is called automatic accommodation. → Due to this most of the blue light (shorter wavelength) are scattered away by the particles. (iii) Even larger particles scatter all the colours of light that is why it appears white. As these slow down by different amounts, different colours are refracted through different angles which causes dispersion. Explain, why a normal eye is not able to see distinctly the objects placed closer than 25 cm. All NCERT textbook questions have been solved by our expert teachers. However, there is lateral displacement. Defects of Vision in Eye (Myopia) Defects of Vision in Eye (Hypermetropia) Refraction of Light through a Glass Prism. What do you understand by spectrum of white light? Structure of Eye. The first prism splits the white light into its seven colour components. 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. Answer: NCERT Class 10 Science Unit 11 is for Human Eye and Colourful World. Question 10. Explore the structure of the ear and its functions only at BYJU’S. Least deviated component: Red (iii) He formed a spectrum from sunlight and placed an identical but inverted prism in front of prism forming the spectrum. The planets are much closer to the earth and are thus seen as extended sources. Question 19. Answer: Why do different rays deviate differently in the prism? Question 1. → This results in fluctuation of apparent position of star. State the cause of dispersion of white light by a glass prism. Atmospheric Refraction Effects. This is called internal reflection. Question 3. (iii) Advanced sunrise and delayed sunset. Pupil: To regulate and control the amount of light entering the eye. 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. A person can see clearly only up to 3 metres. The defect of the eye due to which a person is unable to distinguish between certain colours, is known as colour blindness. Answer: 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. NCERT Solutions for Class 10 Science Chapter 11: The Human Eye and Colourful World. You can also get free sample papers, Notes, Important Questions. Answer: → Human eye: The sense organ that helps us to see. The difference of time is about 2 minutes each for early rise and late setting of the Sun. Question 1: What kind of lens is present in the human eye ? → The amount of light coming from stars also vary due to changing Refractive Index of atmosphere. It provides most of the refraction of light. (b) Curvature increrases. Or Answer: Near point or Least distance of distinct vision, Advantage of the eyes in front of the face. In this article you will get CBSE Class 10 Science chapter 11, Human Eye and Colourful World: NCERT Exemplar Problems and Solutions (Part-II). → 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: 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. This browser for the power of accommodation of human eye, defects vision. 2009 ) answer: for scattering of light travel at the same speed in a of. 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