MAIN POINTS FROM CHAPTER LIGHT. - Class 8 PDF Download

1. Light is a form of radiant energy. 
2. Light may be regarded as a form of electro magnetic radiation. 
3. Light can travel without a medium. 
4. Light has maximum speed of 3*10^8.
5. In a homogeneous medium light travels in a straight line  
6. The velocity of light is different in different media. 
7. The ray of light bends towards a normal as it passes through a rarer medium to denser medium and bends away from a normal when it travels through a denser medium to a rarer medium. 
8. A convex lens converges a parallel beam of light as its focal point and a concave lens diverges a parallel beam of light  
9. The distance between the lens and its focal point is called the focal length of its length. 
10. The more strongly curved a lens is,  the smaller is its focal length  
11. The image of an object formed by a convex lens when object is placed beyond the focal length is real and inverted. 
12. The image of a length formed by the concave length when the object is placed between the lens and focal point is virtual and magnified. 
13. The microscope and the Telescope work by the combination of two appropriate lenses - The objective and eye piece. The final image formed by them is inverted  
14. Near sighted or myopic people cannot see distant objects clearly. This can be corrected by the use of spectacle with concave lens. 
15. The reflection index of water is 1.33 and of glass is  1.50
16. Sunlight Contains a mixture of seven colors  
17. The objective lens of a telescope forms a real image while the eye piece forms a virtual image  
18. Astigmatism is a defect of vision in which lens of the eyes exhibits different curvature in different planes,  corrected by using cylindrical lenses  
19. Presbyopia is an eye defect of advancing age in which the lens of the eye hardens causing loss of ability to focus objects  
20. Diopeter is a unit of power of lens.