BOOK FREE CLASS; COMPETITIVE EXAMS. Write in one word or at the most in one sentence about the following: 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. (2012 OD) Answer: The focal length of eye-lens can be changed by changing its shape by the action of ciliary muscles. Our eye is the most important natural optical instrument. Find the nature, the focal length and the power of the correcting lens used for the defective vision. Question and Answer forum for K12 Students. (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. How is astigmatism corrected? → 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 phenomenon is called dispersion. What do you understand by spectrum of white light? → This results in fluctuation of apparent position of star. This disease can be cured by replacing the defective cornea with the cornea of a donated eye. This is called internal reflection. Answer: A rainbow is a natural spectrum appearing in the sky … Class 10 Class 12. When the cilary muscles are relaxed, the lens becoems thin. Answer: The human ear is an important organ of the human body responsible for hearing and balance. Solution : Convex lens. For an astronaut, the sky would appear dark because in space there is no atmosphere to scatter light. Answer: b. How does atmospheric refraction affect sunrise and sunset? This is why sun appear red in colour. (ii) most contracted state. The eye resembles a - camera in many ways. Solution: 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. Answer: Draw a ray diagram showing the dispersion through a prism when a narrow beam … It is like a camera which has a lens and screen system. Human Eye: working of human eye, Persistence of vision, Power of accommodation of human eye, Defects of vision. The -ve sign with f indicates the concave lens. In most relaxed state. Answer: (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. The blue colour of the sky is due to the scattering of sunlight by the molecules of the atmosphere. Human Eye and Colourful World. Answer: Name the type of lens required by such persons to improve the vision. Answer: Human Eye and Colourful World Extra Questions Very Short Answer Type. → 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. What eye defect is hypermetropia? 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. This defect of the eye is hypermetropia. Question 10. Answer: As rays of all colours emerge in the same direction, i.e., the direction of the incidence of white light, there is no dispersion. 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. → 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 difference of time is about 2 minutes each for early rise and late setting of the Sun. (iv) Retina Malfunctions of Eyes: Cataract: In old age the cornea becomes cloudy. Answer: Question 10. (c) Concave lens. The human eye is the natural convex lens that refracts light. What is meant by dispersion of white light? Extra Questions for Class 10 Science Chapter 11 Human Eye and Colourful World with Answers Solutions. Describe the formation of rainbow in the sky with the help of a diagram. 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. In this article you will get CBSE Class 10 Science chapter 11, Human Eye and Colourful World: NCERT Exemplar Problems and Solutions (Part-II). Millions of people of the developing countries are suffering from corneal blindness. Cornea: Refraction of the light rays falling on the eye. Question 3. Explain why it is so. Answer: Answer: These are more effective in scattering light of shorter wavelengths at the blue end than light of longer wavelengths at the red end. A person needs a lens of power -4.5 D for correction of her vision. Atmospheric Refraction Effects. The person with … Question 17. → The air above hot surface becomes hot and rises. A Glimpse of CBSE Class 10 Science Marking Scheme (b) A glass slab acts as a combination of two identical glass prisms. 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. (iii) Advanced sunrise and delayed sunset. Objectives of organising such campaigns: Question 2. So, danger signs are made in red colour. A rainbow is a natural spectrum appearing in the sky Raindrop after a rain. It has "nearly a spherical shape. Studyrankers is a free educational platform for cbse k-12 students. Prescribe a lens for spectacles so that he can see clearly up to 12 metres. As a result, the cornea has different curvatures in different directions of the horizontal and vertical planes. Write two causes for development of this defect. Answer: Question 8. Thus, scattering of light makes the particles visible. NCERT Exemplar Solutions for Class 10 Science Chapter 11 Human Eye and Colourful world includes the solution to all the questions present in the NCERT Class 10 exemplar textbook. → It is done by using concave lens of appropriate power. The + sign with for the power indicates a convergent lens. This increases the curvature of the eye lens. Question 10. At sunrise and sunset when the sun is below the horizon, the light rays starting from sun are incident on these layers. Class 1 - 3; Class 4 - 5; Class 6 - 10; Class 11 - 12; CBSE. → Since the physical conditions of the earth’s atmosphere are not constant the light from. → Violet is the most deviated colour as it has smallest wavelength in visible spectrum. → Sometimes a person may suffer from both myopia and hypermetropia. (b) Curvature increrases. Solution: State its cause. Class 10 Science MCQs Chapter 11 Human Eye and Colourful World. This is due to. Curvature decreases. Name the component of white light that deviates the least and the component that deviates the most while passing through a glass prism. What causes presbyopia? Cone-shaped retinal cells are responsible for making a person differentiate between colours. The nearest point up to which the eye can see an object clearly without any strain, is called the near point of the eye. To assist you with that, we are here … The human eye(s) are located in the specialized sockets carved out in the human skull. Question 24. Answer: due to decrease in the focal length of the eye lens. Defects of vision and their correction. The Human Eye and Ray Optics - Human Eye and Colourful World, Class 10, Science. Question 1. Tyndall effect can also be observed when sunlight passes through a canopy of a dense forest. Question 2. During sunset and sunrise, the sun is near horizon and therefore the sunlight has to travel larger distance in atmosphere. (ii) correction of myopia using a lens. (i) Cornea 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. 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. This enables us to see distant objects clearly. Question 12. Cataract can be cured by eye surgery. As a result the sun appears higher than its actual position. Question 5. He … (b) The ability of the eye lens to adjust its focal length is called automatic accommodation. Astigmatism. What are the essential parts of the eye and their functions → The near-point of the old person having presbyopia gradually recedes and becomes much more than 25 cm away. Extra Questions for Class 10 Science Chapter 11 Human Eye and Colourful World with Answers Solutions. This enables us to see nearby objects clearly. 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? Question 16. Answer: NCERT Exemplar Class 10 Science Unit 11 Human Eye and Colourful World. Parts of Human Eye • Cornea: It is the outermost, transparent part. → 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. (ii) Medium sized particles scatter mainly the red colour (longer wavelength). Explain giving a reason why the sky appears blue to an observer from the surface of the Earth. → It results in fluctuation in apparent position of object. → Clouds are formed by water vapours. Explain, why a normal eye is not able to see distinctly the objects placed closer than 25 cm. After the dispersion of light and internal reflections, the band of colours reaches observer’s eye in the form of a rainbow. Question 15. How are we able to see nearby and also the distant objects clearly? (a) Myopia Question 3. Answer: Draw a simple diagram of the human eye and label clearly the cornea, iris, pupil, ciliary muscles, eye-lens, retina, optic nerve and blind spot. Why are ‘danger’ signal lights red in colour? (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. The focal length of the eye lens decreases. A student is observing the diagram showing the path of a ray of light passing through a glass prism. Question 22. A collection of questions on CBSE- Human Eye and the Colourful World with solutions created by best teachers are available as a PDF download. Lakhmir Singh Physics Class 10 Solutions The Human Eyes And The Colorful World. NCERT Solutions for Class 10 Science Chapter 11: The Human Eye and Colourful World. 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. A rainbow is always formed in the direction opposite to that of the sun. However, at noon sunlight would travel relatively shorter distance only a little blue and violet colours are reflected and it is nearly the white light which reaches our eye. In fact the sensation produced by the image of an object lasts for nearly 1/16th of a second on retina. What should the appearance of the sky be during the day for an astronaut staying in the international space station orbiting the Earth? Answer: (ii) correction of hypermetropia by using a lens. Eye defects. The twinkling of a star is due to atmospheric refraction of starlight. 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. Question 1. Power of Accommodation of Human Eye: The human eye can clearly see a nearby object as well as an object on infinity. These droplets behave as glass prism. Most deviated component: Violet. Image Formation by Concave Mirror. Formation of Rainbow. 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. This wavering of light is an effect of atmospheric refraction. It is least scattered by fog and smoke and can be seen in the same colour over a long distance. The water droplets act like small prisms. Explain the reason why stars appear to twinkle and the planets do not twinkle. Answer: The light of shorter wavelength (blue) of the visible spectrum is scattered more than the light of longer wavelength by the atmospheric particles. Answer: Question 14. What type of defect of vision is he suffering from? → When the sun is below horizon, the rays have to pass from rarer to denser medium. Human Eye and Colourful World - Know the working of a human eye, the difference between Cornea and Retina. Causes of hypermetropia: This defect arises because either: Hypermetropia can be corrected by using convex lens of suitable focal length in spectacles. Question 4. Answer: The layers of air nearer to earth are denser than those above it. (b) What is the focal length of the corrective lens? 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. Since the atmosphere consists of varying densities the apparent position of the object, as seen through the hot air fluctuates. The molecules of air and other fine particles in the atmosphere have size smaller than the wavelength of visible light. Answer: The refractive index of hot air is less than that of cool air. Given: = -25 cm. Hence sun appears red. Question 1: What kind of lens is present in the human eye ? How is presbyopia corrected? Answer: → Such people require bifocal lens for correction. CBSE Previous Year Question Paper for Class 10, CBSE Previous Year Question Paper for Class 12. Per second is because focal length in spectacles to that of blue light ( shorter wavelength ) are located the. M should be used in its path becomes visible when light passes through a glass prism objects. 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