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Physic Light:- Reflection and Refraction, V.S, tuition centre Itis a form of energy /which produces sensation of sight in us. _ Properties of light: © Light travel in a straight line. © It does not need any material medium to travel ie. it also travel in vacuum. * The speed of light in vacuum is 300000 km/sec or 3X10 m/sec. » Speed of light is different in different media. L E E Be | Souroes of ant -Asource —— e.. is an object from which light is given out. ; Source of light can be natural and manmade for e.g. Sun is natural source of light and electric | lamp , Candle etc. are man-made. | Medium i ‘Any substance through which light can pass is called a medium. ‘Transparent medium: - The medium which allow light to pass through it is called transparent medium. For example: - Glass, Water, etc. Translucent medium: - The medium which allow light to pass through it partially. For example: - Butter paper, Grounded, glass, etc. ‘Opaque medium: - The medium which does not allow light to pass through it is called opaque medium. For example: - Wood, still board, etc. Some important terms related to light Physicy Light: Reflection and Refractiow V.S. thittow cent, 2.) Beam of light: - A group of light rays travelling together is called beam of light. Abeam oflight in which all | Abeamoflightin which all A beam of light in which rays _ Rays travel parallel to each rays go to meet at a point. Come out from a point Other. Source. The phenomenon of bouncing back of light in same medium after striking the reflecting surface “called reflection of light. The reflection of parallel beam of light after striking from a smooth and well-polished surface in a particular direction is called a regular reflection. Note: In this reflection we see source of light. , 7 V5, MM og Physicy Light:- Reflection and Refrackiow aq . F reflection Asmooth, shiny or pollshed surface that forms Image by 18 Plane Mirror A plane mirror is a mirror with a flat reflective surface. ‘Characteristics of image formed by plane mirror:- Following are the important characteristics of image formed by plane mirror. as. The image of real object is always virtual such an image cannot be taken of screen. The image formed in a plane mirror is always Erect. The size of image in plane mirror is always the same as the size of object. The image formed in the plane mirror is laterally inverted i.e. left side of the object ben the right side of the image. a The image formed in a plane mirror is as febehind the mirror as the object is in frontal mirror. fox us Convex When a ray of light is incident normally on a mirror than after mes reflection it will retracted its path so, zi = Zr=0. A spherical mirror is that mirror whose reflecting surface is a part of hollow sphere of glass. 4 V.S. tuittow centre physice Light:- Reflection and Refraction phere are 2 types of spherical mirror:- 4) Concave mirror (Converging) 2.) Convex mirror (Diverging) Outer Inner Reflective ~ reflective ™ ~~, soncave mirror is that spherical mirror in which reflecting surface is towards the center of the phere of which the mirror is a part. rSUSES: e AConcave mirror is used as a reflection in torch, search light, head lights of motor vehicle etc. to get powerful parallel beams of lights. « AConcave mirror is used as doctors head mirror to focus light o ears, nose thread etc. to be examined. » The dentists are concave mirrors to observe large image of the teeth of patient. * Large concave mirrors are also used in reflecting type's telescopes. * Large concave mirrors are also used to concentrate sunlight to produce heat in solar cookers, solar furnaces etc. n body parts like eyes, onvex mirror is that spherical mirror in which reflecting surface is away from the center of the phere of which the mirror is the part. * Aconvex diverse over a large area. A Convex mirror is used by diverse of automobiles like cars, trucks and buses as a rear view mirror these mirror are fitted on the sides of the vehicle enable the a river to see traffic be kind of safe driving this is because, aA concave mirror produces an erect image of the objects. b,) Size of image formed by a convex mirror is much smaller than the objects. mirror is used as reflection in street lamps. As a result, light from the lamp 5| ; Light.- Reflection and Refractiow V.S. tuition centre, At the focus F | Real, inverted and point-sized ; {b) Between infinity | Between F and-C| Real, smaller than and the centre the object and of curvature C inverted = | Physicy (ce) (d) Light:- Reflection ALC Between C and F and Refraction ALC Between C and infinity | Real, enlarged and VS. tuition, - "ry Real, same size and inverted inverted ACF At infinity Real, infinitely large = E and inverted D P Infinity (6 Between the Behind the Virtual, enlarged pole P and F mirror and erect a ee eh meres 2 = Conver Ray diagram for images formed by Geneave mirror: Between Behind the Virtual, smaller end | infinity and mirror between | erect the pole the focus and the pole tb) At infinity Behind the Virtual, point-sized: mirror at the and erect focus F Phy, Lights- Reflection and Refraction ~ aia see Refraction of fight:- f light when it enters obliquely from one transparent Medium te Phenomenon of bending ea is known as refraction of light. an 8 m/s. * Speed of light is maximum in vacuum. me is 3x10 / * Causes of reflection = change in speed of lig Laws of refraction Incident ray Boundary. Refracted ray ¢ Snell’s law : The ratio of sin of angle of incidence to the sin of an gle of refraction is alwa a constant, for a given pair of media. sini = constant sinr © The incident ray, the refracted ray and the normal to the interface of media at the point of incidence, two transparent all lie in the same plane. : Optically denser medium Out of two given medium, the mediu a m with higher value of refractive index is known as optical denser medium. Optically rarer medium Out of two given medium, the medium with lower val a : , Ue of refractive i i | rarer medium. index is known as optica 10 | hy sics: Light:- Reflection and Refractiow V.S. tuition centre when light enters obliquely from denser to a When light enters obliquely from rarer to a _ arer medium, then it bends away from the denser medium, then it bends towards the ; ormal. normal. Normal Normal Denser Rarer (ny <2) Key) (ny ' Rarer Denser (n,) (n,) r r
