CBSE Class 10 Science Chapter 10 - Light Reflection and Refraction

Brief Information: In NCERT Class 10 Science Chapter 10, we will study the phenomena of reflection and refraction of light using the straight-line propagation of light. These basic concepts will help us in the study of some of the optical phenomena in nature. The chapter also discusses the reflection of light by spherical mirrors and refraction of light and their application in real life. Light is a source of energy which generates a sensation of vision in human beings. Light seems to travel in straight lines. The different types of a spherical mirror, convex and concave are taught. The various terms related to spherical mirrors like the centre of curvature, the radius of curvature, etc, focus, pole, etc are discussed with ray diagrams. Uses of a spherical mirror are also discussed in this chapter. Mirror formula gives the relationship between the object-distance, image-distance, and focal length of a spherical mirror. The focal length of a spherical mirror is equal to half its radius of curvature.

Refraction is the bending of a wave when it enters a medium where its speed is different. The refraction of light when it passes from a fast medium to a slow medium bends the light rays toward the normal to the boundary between the two media. The phenomena of refraction can be understood easily by the concepts of the refractive index and optical density. The refractive index of a transparent medium is the ratio of the speed of light in a vacuum to that in the medium. In case of a rectangular glass slab, the refraction takes place at both the air-glass interface and glass-air interface. The emergent ray is parallel to the direction of the incident ray. Lens formula gives the relationship between the object-distance, image-distance, and the focal length of a spherical lens. Power of a lens is the reciprocal of its focal length. The SI unit of power of a lens is dioptre.

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