refraction of light class 10 | laws of refraction class 10 | 10th class Physics | punjab, federal

Tite of this video refraction of light sabaq | 10th physics wallah chapter 12 hindi | refraction of light in urdu atifahmedofficial atifahmadofficial 12.4 REFRACTION OF LIGHT If we dip one end of a pencil or some other object into water at an angle to the surface, the submerged part looks bent as shown in Fig.12.7. Its image is displaced because the light coming from the underwater portion of the object changes direction as it leaves the water. This bending of light as it passes from one transparent medium into another is called refraction. Refraction of light can be explained with the help of Fig.12.8. A ray of light IO travelling from air falls on the surface of a glass block. Fig. 12.8: Refraction of light by a glass block At the air-glass interface, the ray of light IO changes direction and bends towards the normal and travels along the path OR inside the glass block. The rays and OR are called the incident ray and IO the refracted ray respectively. The angle ‘i’ made by SUMMARY  When light travelling in a certain medium falls on the surface of another medium, a part of it turns back in the same medium. This is called reflection of light. There are two laws of reflection: i. The incident ray, the reflected ray, and the normal all lie in the same plane. ii. The angle of incidence is equal to the angle of reflection (i.e., i = r).  Like plane surfaces, spherical surfaces also reflect light satisfying the two laws of reflection.  In mirrors, image formation takes place through reflection of light while in lenses image is formed through refraction of light.  The equation relating the distance of the object p from the mirror/lens, distance of the image q and the focal length f of the mirror/lens is called mirror/lens formula, given by  Magnification of a spherical mirror or thin lens is defined as “the ratio of the image height to the object height.” i.e.,  Power of a lens is defined as “the reciprocal of its focal length in metres”. Thus Power of a lens = P = 1 / focal length in metres. The SI unit of power of a lens is “Dioptre”, -1 denoted by a symbol D. If is expressed in metres so that 1 D = 1 m . Thus, 1 Dioptre f is the power of a lens whose focal length is 1 metre.  The refractive index ‘n’ of a material is the ratio of the speed of light ‘c’ in air to the speed of light ‘v’ in the material, thus  The bending of light from its straight path as it passes from one medium into another is called refraction.  Refraction of light takes place under two laws called laws of refraction. These are stated as: i. The incident ray, the refracted ray, and the normal at the point of incidence The angle of incidence for which the angle of refraction becomes 90 is called critical angle. When the angle of incidence becomes larger than the critical angle, no refraction occurs. The entire light is reflected back into the denser medium. This is known as total internal reflection of light.  A simple microscope, also known as a magnifying glass, is a convex lens which is used to produce magnified images of small objects.  A compound microscope is used to investigate structure of small objects and has two converging lens, the objective and the eyepiece.  Telescope is an optical instrument which is used to observe distant objects using lenses or mirrors. A telescope that uses two converging lenses is called refracting telescope. A telescope in which the objective lens is replaced by a concave mirror is called reflecting power telescope.  The magnifying power is defined as “the ratio of the angle subtended by the image as seen through the optical device to that subtended by the object at the unaided eye”.  The resolving power of an instrument is its ability to distinguish between two closely placed objects.  The ability of the eye to change the focal length of its lens so as to form a clear image of an object on its retina is called its power of accommodation.  The disability of the eye to form distinct images of distant objects on its retina is known as nearsightedness. The nearsighted eye can be corrected with glass or contact lenses that use diverging lenses Light rays from the distant objects will . diverge by this lens before entering the eye.  The disability of the eye to form distinct images of nearby objects on its retina is known as farsightedness. This defects can be corrected with the aid of a suitable converging lens. The lens refracts the light rays more towards the principal axis before they enter the eye. refractionOfLight #refraction #refractionThroughGlassSlab #sabaq #10th #10thphysics #freeOnlineClases #freeVideoLectures #10thclassphysics #class10 #urdu #hindi #10thPhysics #physics #lecture #freeOnlineClasses #matricPart2 #10th #videolecture #atifahmedofficial #atifahmadofficial