{"id":811857,"date":"2024-03-13T16:17:36","date_gmt":"2024-03-13T10:47:36","guid":{"rendered":"https:\/\/leverageedu.com\/discover\/?p=811857"},"modified":"2024-03-13T16:17:36","modified_gmt":"2024-03-13T10:47:36","slug":"ncert-class-8-science-chapter-13","status":"publish","type":"post","link":"https:\/\/leverageedu.com\/discover\/school-education\/ncert-class-8-science-chapter-13\/","title":{"rendered":"NCERT Class 8 Science Chapter 13 ‘Light’: Notes and Solutions (Free PDF)"},"content":{"rendered":"\n

Well-written notes help us cover the chapter in its entirety and serve as a quick revision tool that becomes essential when preparing for our exams. Keeping the same in mind, we have prepared NCERT Solutions and Notes for Class 8 Science Chapter 13: Light. In the notes, you will find a summary of all important concepts and theories in the lesson. Also, you will come across key definitions in the chapter. As you proceed through the notes, you also get NCERT solutions to questions in the chapter and PDF for the same. Let\u2019s start learning.<\/p>\n\n\n\n

Download the NCERT Class 8 Science Chapter 13 Solutions PDF Here!<\/strong><\/a><\/p>\n\n\n\n\n\n\n

Explore Notes of all the Chapters of Class 8 Science:<\/strong><\/p>\n\n\n\n

Chapter 1<\/strong><\/a><\/td>Chapter 2<\/strong><\/a><\/td>Chapter 3<\/strong><\/a><\/td><\/tr>
Chapter 4<\/strong><\/a><\/td>Chapter 5<\/strong><\/a><\/td>Chapter 6<\/strong><\/a><\/td><\/tr>
Chapter 7<\/strong><\/a><\/td>Chapter 8<\/strong><\/a><\/td>Chapter 9<\/strong><\/a><\/td><\/tr>
Chapter 10<\/strong><\/a><\/td>Chapter 11<\/strong><\/a><\/td>Chapter 12<\/strong><\/a><\/td><\/tr>
Chapter 13<\/td><\/td><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

NCERT Class 8 Science Chapter 13 Light: Notes<\/h2>\n\n\n\n

In NCERT Class 8 Science Chapter 13, we will learn about light, what are the laws of reflection, how the human eye works, etc. Let\u2019s start with the chapter.<\/p>\n\n\n\n

What are the Laws of Reflection?<\/h3>\n\n\n\n
    \n
  • The ray of light that strikes a surface, is known as the incident ray<\/strong>.<\/li>\n\n\n\n
  • The ray of light that comes back after getting reflected from the surface is known as reflected ray<\/strong>.<\/li>\n\n\n\n
  • A line drawn perpendicular to a surface is known as the normal<\/strong>.<\/li>\n\n\n\n
  • The angle between the normal and the incident ray is known as the angle of incidence<\/strong>.<\/li>\n\n\n\n
  • The angle between the normal and the reflected ray is known as the angle of reflection<\/strong>.\u00a0<\/li>\n\n\n\n
  • There are basically two laws of reflection:<\/li>\n<\/ul>\n\n\n\n
    The angle of incidence is always equal to the angle of reflection.<\/td><\/tr>
    The incident ray, the normal, and the reflected ray, at the point of incidence, all lie in the same plane.\u00a0<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
      \n
    • Features of an image formed on a plane mirror are:<\/li>\n<\/ul>\n\n\n\n
        \n
      1. The image formed is straight.\u00a0<\/li>\n\n\n\n
      2. The image formed is the same distance as the object in front of the mirror.<\/li>\n\n\n\n
      3. The image formed is laterally inverted.\u00a0<\/li>\n\n\n\n
      4. The image formed is of the same size as that of the object.<\/li>\n\n\n\n
      5. It is a virtual image.\u00a0<\/li>\n<\/ol>\n\n\n\n
          \n
        • In an image formed by a mirror, the object\u2019s left appears on the right and the right appears on the left. This is known as lateral inversion<\/strong>.<\/li>\n<\/ul>\n\n\n\n

          \"Class<\/h3>\n\n\n\n

          What are Regular Reflection and Diffused Reflection?<\/h3>\n\n\n\n
            \n
          • Regular reflection is defined as the reflection that takes on a smooth surface and the reflected rays all have the same angle of reflection and are parallel to each other.<\/li>\n\n\n\n
          • Diffused or irregular reflection is defined as the reflection that takes place on an irregular or rough surface. The reflected rays have different angles of reflection and are not parallel to each other.\u00a0<\/li>\n\n\n\n
          • The objects which shine in the light of other objects are called illuminated objects<\/strong>. For Example: the Moon.<\/li>\n\n\n\n
          • The objects which emit their own light are known as luminous objects<\/strong>. For Example: The Sun.\u00a0<\/li>\n<\/ul>\n\n\n\n
            Note that: <\/strong>The diffused reflection is not due to the failure of the laws of reflection. It is caused by the irregularities in the reflecting surface, like that of cardboard.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

            \"Class<\/h3>\n\n\n\n

            What is the Concept of Multiple Images?<\/h3>\n\n\n\n
              \n
            • When two plane mirrors are placed parallel to each other, then the number of images formed is infinite. If not placed parallel to each other, then still multiple images are formed.<\/li>\n\n\n\n
            • This is because, after being reflected once, light can be re-reflected multiple times.<\/li>\n\n\n\n
            • This concept is used by periscopes that are found in submarines and kaleidoscopes also use this concept.<\/li>\n<\/ul>\n\n\n\n
              Note That: <\/strong>The sunlight is referred to as white light and consists of seven colours.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

              \"Class<\/h3>\n\n\n\n

              The Human Eye<\/h3>\n\n\n\n
                \n
              • Our eye is roughly spherical in shape.<\/li>\n\n\n\n
              • The outer coat of our eye is white and tough in nature to protect our eye from damage. Its transparent front part is known as the cornea<\/strong>.\u00a0<\/li>\n\n\n\n
              • Behind the cornea, we find a dark muscular structure called the iris<\/strong>. The iris is that part of the eye that gives it its distinctive colour<\/li>\n\n\n\n
              • In the iris, there is a small opening called the pupil<\/strong>. The size of the pupil is controlled by the iris.<\/li>\n\n\n\n
              • The iris controls the amount of light entering into the eye.<\/li>\n\n\n\n
              • Behind the pupil of the eye is a lens<\/strong> which is thicker in the centre.<\/li>\n\n\n\n
              • The lens focuses light on the back of the eye, on a layer called the retina<\/strong>.<\/li>\n\n\n\n
              • The retina contains several nerve cells. Sensations felt by the nerve cells are then transmitted to the brain through the optic nerve.\u00a0<\/li>\n\n\n\n
              • There are two kinds of cells\u2013\u00a0<\/li>\n<\/ul>\n\n\n\n
                  \n
                1. Cone Cells, which are sensitive to bright light. Cones sense colour.<\/li>\n\n\n\n
                2. Rod Cells, which are sensitive to dim light<\/li>\n<\/ol>\n\n\n\n
                    \n
                  • At the junction of the optic nerve and the retina, there are no sensory cells, so no vision is possible at that spot. This is called the blind spot<\/strong>.<\/li>\n\n\n\n
                  • Eyelids prevent any object from entering our eyes.\u00a0<\/li>\n\n\n\n
                  • The most comfortable distance at which one can read with a normal eye is about 25 cm.<\/li>\n\n\n\n
                  • Sometimes, particularly in old age, eyesight becomes foggy. It is due to the eye lens becoming cloudy. When it happens, persons are said to have cataract<\/strong>. There is a loss of vision, sometimes extremely severe.<\/li>\n\n\n\n
                  • It is possible to treat this defect. The opaque lens is removed and a new artificial lens is inserted. Modern technology has made this procedure simpler and safer.<\/li>\n<\/ul>\n\n\n\n

                    \"Class<\/h3>\n\n\n\n

                    How can we take care of our eyes?<\/h3>\n\n\n\n
                      \n
                    • Have regular check-ups from an eye specialist.\u00a0<\/li>\n\n\n\n
                    • Wear spectacles.<\/li>\n\n\n\n
                    • Do not look at the Sun or a powerful light directly.<\/li>\n\n\n\n
                    • Never rub your eyes.<\/li>\n\n\n\n
                    • Wash your eyes periodically.\u00a0<\/li>\n\n\n\n
                    • Always read at the normal distance for vision.<\/li>\n\n\n\n
                    • One should include in the diet components which have vitamin A because it is good for our eyes. Raw carrots, broccoli, green vegetables (such as spinach) and cod liver oil are rich in vitamin A. Eggs, milk, curd, cheese, butter and fruits such as papaya and mango are also rich in vitamin A.<\/li>\n<\/ul>\n\n\n\n

                      How can Visually Impaired Persons Can Read and Write?<\/h3>\n\n\n\n
                        \n
                      • Persons who are visually impaired try to identify things by touching and listening to voices more carefully.<\/li>\n\n\n\n
                      • They develop their other senses more sharply.<\/li>\n\n\n\n
                      • However, additional resources can enable them to develop their capabilities further.<\/li>\n\n\n\n
                      • Non-optical aids include visual aids, tactual aids (using the sense of touch), auditory aids (using the sense of hearing) and electronic aids. Visual aids can magnify words, can provide suitable intensity of light and material at the proper distance.<\/li>\n\n\n\n
                      • Tactual aids, including Braille writer slate and stylus, help the visually challenged persons in taking notes, reading and writing.<\/li>\n\n\n\n
                      • Auditory aids include cassettes, tape recorders, talking books and other such devices.<\/li>\n\n\n\n
                      • Electronic aids, such as talking calculators and computers, are also available for performing many computational tasks.<\/li>\n\n\n\n
                      • Optical aids include bifocal lenses, contact lenses, tinted lenses, magnifiers and telescopic aids. While the lens combinations are used to rectify visual limitations, telescopic aids are available to view chalkboard and class demonstrations.<\/li>\n<\/ul>\n\n\n\n

                        What is the Braille System?<\/h3>\n\n\n\n
                          \n
                        • The most popular resource for visually challenged persons is Braille.<\/strong><\/li>\n\n\n\n
                        • Louis Braille, himself a visually challenged person, developed a system for visually challenged persons and published it in 1821.<\/li>\n\n\n\n
                        • The present system was adopted in 1932.\u00a0<\/li>\n\n\n\n
                        • There is Braille code for common languages, mathematics and scientific notation. Many Indian languages can be read using the Braille system.<\/li>\n\n\n\n
                        • Braille texts can be produced by hand or by machine. Typewriter-like devices and printing machines have now been developed.<\/li>\n<\/ul>\n\n\n\n

                          Also Check Out<\/strong><\/p>\n\n\n\n

                          Reflection of Light: Definition, Types, Laws & More<\/strong><\/td><\/tr>
                          NCERT Class 7 Science Chapter 11 Light<\/strong><\/a><\/td><\/tr>
                          NCERT Solutions and Notes for Class 6 Science Chapter 8<\/strong><\/a><\/td><\/tr>
                          Total Internal Reflection: Definition, Properties & Examples<\/strong><\/td><\/tr>
                          Why Sky is Blue in Colour?<\/strong><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
                          \n