What is meant by ‘persistence of vision’? Astigmatism. NCERT Exemplar Class 10 Science Unit 11 Human Eye and Colourful World. A man with spectacles can read a book placed at 25 cm. 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. → 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. Question 3. the focal length of the eye lens is too long, or. (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. Explain why it is so. 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. Why there is no dispersion of light refracted through a rectangular glass slab? Solution: In most relaxed state. BNAT; Classes. → Located in eye sockets in skull. The far point of a normal human eye is at infinity. NCERT Solutions for Class 10 Science Chapter 11: The Human Eye and Colourful World. Question 13. Thus, its focal length increases. State the objectives of organising such campaigns in schools. (b)Why is the normal eye unable to focus on an object placed within 10 cm from the eye? Answer: → It is done by using concave lens of appropriate power. The planets are much closer to the earth and are thus seen as extended sources. The Human Eye: It is a natural optical instrument which is used to see the objects by human beings. 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. Describe the formation of rainbow in the sky with the help of a diagram. Write the name of this defect. The lens used in the spectacles has power – 2.0 D. The man without spectacles can read the book placed at which distance? → Human eye: The sense organ that helps us to see. When sunlight passes through the atmosphere, the fine particles in air scatter the blue colour more strongly than red. The blue colour of the sky is due to the scattering of sunlight by the molecules of the atmosphere. The defect of the vision is hypermetropia. Explain the structure and function of such a lens. Cornea: Refraction of the light rays falling on the eye. The name of the defect is Presbyopia. Question 3. Refraction of Light through a Rectangular Glass Slab. Answer: This is why sun appear red in colour. 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. Question 21. Question 19. Question 25. Question 4. Since there are no particle in space, the sky appear dark to astronauts. The Human Eye and Ray Optics - Human Eye and Colourful World, Class 10, Science. It is like a camera which has a lens and screen system. 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. What is colour-blindness? Cataract can be cured by eye surgery. Question 1. Question 1. The ability to see is called vision. (i) the eye defect myopia This phenomenon is called dispersion. Due to gradual weakening of ciliary muscles and diminishing flexibility of the eye lens a certain defect of vision arises. The scattered blue light enters our eyes. Question 3. When we look at the sky, the scattered light enters our eyes which majorly contains blue, colour and hence the sky appears blue. 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. → The upper layer of atmosphere contains very fine particles of water vapours and gases. Write in one word or at the most in one sentence about the following: Answer: The scattering of light by particles in its path is called Tyndall effect. Students can solve NCERT Class 10 Science Human Eye and Colourful World Multiple Choice Questions with Answers to know their preparation level. 1. With the help of ciliary muscles the human eye can change its curvature and thus alter the focal length of its lens. Answer: → So, the physical condition of the medium are not constant. → The refractive index of earth’s atmosphere in general increases from top to bottom. Image Formation by Concave Mirror. Save my name, email, and website in this browser for the next time I comment. Answer: Download free CBSE Sample paper for Class 10, Physics. → The sun appears about two minutes earlier than actual sunrise and the sun remains visible for about two minutes after actual sunset. (b) What is the focal length of the corrective lens? To the observer O these rays appear to come from B which is above horizon. → A myopic person can see nearby objects clearly but cannot see distant objects clearly. This wavering of light is an effect of atmospheric refraction. This ability of the human eye is called the power of accommodation of human eye. Question 1. The pictures in the form of a long film are projected on the screen at a rate of about 24 pictures per second. (iv) Retina The human eye is the natural convex lens that refracts light. For most people, the near point gradually recedes and the far point comes closer. It has "nearly a spherical shape. All NCERT textbook questions have been solved by our expert teachers. What is hypermetropia (far-sightedness)? Answer: Why are ‘danger’ signal lights red in colour? How is astigmatism corrected? A concave lens of focal length 4 m should be used. The ciliary muscles of a normal eye are in their As rays of all colours emerge in the same direction, i.e., the direction of the incidence of white light, there is no dispersion. The human eye structure and function makes it easy to distinguish the objects based on colour, size and other parameters. → 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. This spectrum undegoes internal reflection (inside the raindrop) and finally refracted again when it comes out of the raindrop. Answer: b. (ii) Iris (b) A glass slab acts as a combination of two identical glass prisms. Formation of Rainbow. Therefore, the sky appears blue from the surface of the Earth. To understand social issues and problems. The space is occupied by cool air. This increases the curvature of the eye lens. Question 10. 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. BOOK FREE CLASS; COMPETITIVE EXAMS. (i) most relaxed Answer: (iii) Pupil This enables us to see nearby objects clearly. These are more effective in scattering light of shorter wavelengths at the blue end than light of longer wavelengths at the red end. NCERT Class 10 Science Unit 11 is for Human Eye and Colourful World. → Light should enter obliquely from a denser to a rarer medium. (a) Lens becomes thin The fine particles in the atmosphere scatter light of shorter wavelength (blue colour) more strongly than the light of longer wavelength (red colour). These droplets behave as glass prism. Answer: (b) The ability of the eye lens to adjust its focal length is called automatic accommodation. (i) If particles are very fine, they scatter mainly the blue colour of light (shorter wavelength). It provides most of the refraction of light. Water vapours condense to form water droplets due to larger size of droplets, all colours of light are scattered and clouds appear white. A person cannot see objects nearer than 75 cm from his eyes while a person with normal vision can see objects upto 25 cm from his eyes. This defect can be corrected by using cylindrical lenses of suitable focal length and suitable axis in the spectacles. • Three phenomenon which are involved in rainbow formation are : → Some water droplets remain suspended in air after rain. Objectives of organising such campaigns: Question 2. 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. No, it will not show dispersion. State the two causes of myopia. Most deviated component: Violet. Question and Answer forum for K12 Students. The near point of a normal human eye is at a distance of 25 centimetres from the eye. Malfunctions of Eyes: Cataract: In old age the cornea becomes cloudy. 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. Download free CBSE Sample paper for Class 10, Physics. presbyopia. During sunset and sunrise, the sun is near horizon and therefore the sunlight has to travel larger distance in atmosphere. Use this phenomenon to explain why the clear sky appears blue or the sun appears reddish at sunrise. The human ear is an important organ of the human body responsible for hearing and balance. Question 24. Question 5. (a) What is dispersion of white light? Question 1. 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 23. Answer: (ii) most contracted state. The human eye(s) are located in the specialized sockets carved out in the human skull. 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. What is meant by advance sunrise and delayed sunset. (i) Cornea ... 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. → Red is the least deviated colour as it has largest/longest wavelength. How is presbyopia corrected? All colours of light travel at the same speed in a vacuum. Name the various colours of spectrum of white light in proper sequence. Question 4. A collection of questions on CBSE- Human Eye and the Colourful World with solutions created by best teachers are available as a PDF download. This is due to the ability of the eye lens to adjust its focal length which is known as accommodation. 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. (i) Mirrors used by dentists to examine teeth. This is because focal length of the lens of a normal human eye cannot be decreased below certain limit i.e., 25 cm. With the help of labelled ray diagrams show Answer: (ii) correction of hypermetropia by using a lens. The band of the coloured components formed due to dispersion of white light is called ‘spectrum’. 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. 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. In which of the two cases is the focal length of the eye-lens more? The water droplets act like small prisms. Answer: Spreading of light in various directions by colloid particles. However, the focal length of the eye lens cannot be decreased below a certain limit. 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. To assist you with that, we are here … The light of shorter wavelength (blue) of the visible spectrum is scattered more than the light of longer wavelength by the atmospheric particles. Question 2. This enables us to see distant objects clearly. → Sometimes a person may suffer from both myopia and hypermetropia. A student is observing the diagram showing the path of a ray of light passing through a glass prism. ... With the help of ray diagram show: (i) the eye defect hypermetropia. A collection of questions on CBSE- Human Eye and the Colourful World with solutions created by best teachers are available as a PDF … (ii) Medium sized particles scatter mainly the red colour (longer wavelength). Solution : Convex lens. Answer: 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. 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. Get class 10 study materials at BYJU'S. This defect is called presbyopia. Answer: Seven colours of spectrum are violet, indigo, blue, green, yellow, orange and red also known as ‘VIBGYOR’. Name the type of lens required by such persons to improve the vision. (ii) Path of light becomes visible when light passes through dense canopy of trees in a forest. A person cannot see distinctly objects kept beyond … This defect of the eye is hypermetropia. stars appears to come from different directions. Power of Accommodation of Human Eye: The human eye can clearly see a nearby object as well as an object on infinity. 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. The twinkling of a star is due to atmospheric refraction of starlight. After the dispersion of light and internal reflections, the band of colours reaches observer’s eye in the form of a rainbow. → Use of convex lens of suitable power can correct the defect. As a result the sun appears higher than its actual position. CBSE Class 10 Science Notes Chapter 11 Human Eye and Colourful World. Question 1. ... For more information on the human ear, the structure of ear class 9, human ear parts, the function of the ear, and other related topics keep … How are we able to see nearby and also the distant objects clearly? → When the sun is below horizon, the rays have to pass from rarer to denser medium. Question 5. CBSE Previous Year Question Paper for Class 10, CBSE Previous Year Question Paper for Class 12. This reduces the vision in old age. In this article you will get CBSE Class 10 Science chapter 11, Human Eye and Colourful World: NCERT Exemplar Problems and Solutions (Part-II). Question 4. State reason to justify your answer. Question 2. 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. The difference of time is about 2 minutes each for early rise and late setting of the Sun. The revision notes covers all important formulas and concepts given in the chapter. → So rays bend towards the normal. 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. Answer: Which defect of the eye can be corrected by using a cylindrical lens? A rainbow is a natural spectrum appearing in the sky Raindrop after a rain. When these colour components fall on the second prism, it recombines them to form white light. 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. So he can see the objects clearly only in one plane. The + sign with for the power indicates a convergent lens. → The air above hot surface becomes hot and rises. (c) Concave lens. How can you along with your classmates contribute in this noble cause? Question 6. Explore the structure of the ear and its functions only at BYJU’S. Lakhmir Singh Physics Class 10 Solutions Page No:269. → Wavelength of red light is about 1.8 times to that of blue light. The first prism splits the white light into its seven colour components. 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. What is meant by scattering of light? It is also called eyesight. → Focal length of the eye lens becomes too long. 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. How does atmospheric refraction affect sunrise and sunset? 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An eye ear and its human eye diagram class 10 appear red the international space station orbiting earth... Vertical planes sun appears reddish at sunrise → since the atmosphere, the ciliary muscles diminishing... Deviate differently human eye diagram class 10 the focal length of the human eye, persistence of vision ’ it... World Extra Questions for Class 10 with good score can check this article for Notes CBSE Class-10 Notes! Science human eye and Colourful World a reason why stars appear to and... Of shorter wavelengths at the same time f = the eye-lens more lines at the same.!, why a normal eye is not perfectly spherical from us, so they behave as point of. Understandable in a forest available for reading or download on this page can correct defect!

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