Light- Reflections & Refractions

Retention LightRefraction HANDWRITTEN NOTES -, - - -y Designed with Bama . Snobhit Nirwan

⑨ Light travels in a straight line ⑥ . REFLECTION cominga back of light rays to the same medium , when they fall on surface . # LAWS of Reflection: i*saAInndncgreiledfleeocfntetidnracriydageynncaoelrlkmliitae-l AiannttghthekeospafomrieneHtpol.affnri)en. c iden ce . ooAnnyaramy irorfolrighist }K3B own path . which is ibnaccikdeanlot ngnoirtms ally .. reflected n ; Normal Object Point of intersection incident .is called object . Image intersection called Point of reflected is . ° - of ray - of image° ray Real Image virtual Image It the light rays coming from a Hafeteigr hretflreacytsioncomdoinesg from a point, paint actua l ly , meet a frteeralreflection, rmed is . not meet actually then image fo but appear to meet at another point then image formed Ps virtual . Trick :- def light vo Real , set Aet E virtual . r Ii - go.pt?.af.noghtEd\" real s ± i.- ' > - ! - s -- object i ' -(Inrteerf-sleeccttIeimodnargoaeyf s) z line.tn?sedecnttfnoayts, e y s - 780 ←- ' I ' Red- Reflected rays Black > Incident rays Plane mirror ° Object a nladisteirrmaelalaylgienthveeanrtreeidmeai.qgeu.eildeiwfsttiallsnebteemfsvroitromtubaelthareingdphlatvniceaen-mdveirrsroar. ° If object ° Image is vice-versa ° Size of image is equal to size of object . ° Uses → looking glass , periscopes etc .

Spherical Mirror right ② G whose reflecting surfaces are spherical :. in (IT mirror Ets sphere # et part # El ) ÷m'oiYak !Conn-iffYaga ! a. p Reflecting Reflecting * ← for etfxatmhptleHT surface surface UET ¥• c Patil ITT I 6 ¥3# spherical mirror Ittf et th imaginary sphere 14h17 IF 3114T 314 HIT tht IF 3ft sphere af * mirror FI ° Radius of Curvature: Radius of curvature of a spherical mirror is the radius of imaginary sphere of which , mirror is part . imaginaryo centre of curvature : centre of that sphere of which , mirror ispart. o Pole : It is the mid- point of its reflecting surface . Symbols P . ° Principal Axis : line paining pole and centre of curvature . ° Focus Cfl : A point on principal axis of the mirror at which the light rays coming parallel to principal axis , after reflection actually meet . - !f← n focus of concave → Real '- ! !! !q . I- , convex → virtual . F- : >¥ focal length → Distance between It pole and focus . if )in mirror@my ff=RzT ° Aperture : diameter of reflecting surface ← of spherical mirror . RAY DIAGRAMS ns.gmagrpuaiuaiieitoprinuopaeaxissatterretk¥ \"\" ÷ ÷. will pass through the principal focus in case . !!of a concave mirror or appear to diverge from the .. principal focus in case of a convene mirror . .

passing principal• Amprriinrarcyoipralofrocausrathyorfowuaghhicchorinsedr imreicrfroteocudrs,toaowfftaearrdsrceoftnlheccaetvioen ;¥÷÷;÷ . ' ③ will emerge parallel to principal axis . \" . ÷. . \"2%89:sings:O:Kassite'deft#inattention. ' .÷÷: . , centre of curvature of a convex mirror , after reflection , is reflected back along same path . ÷. The incident . ° and reflected rays make , -1 equal angles EE with principal axis . . i c P It p c Eri 1- , # IMAGE FORMATION BY CONCAVE MIRROR: 'EM # By convex mirror :. ftp.go wsahpeetocHnsoaeintrfodeiiobnnjwieptsceeotoscfiitsoidtonhisnasettiaidsnoienc,brefjweiofnchrnoti.elt.mynyftirwmosaobtniljryedr,cotrti.hse Uses of convex Mirror : o Rear view mirrors in vehicles bivmeiceaawguseeasatnthdheeyyhaavalwereaywcsuidrgveievrde an erect fioeuldtwoaf rd ° Bseigc convex mir rors used as shops Uses of concave mirror :- u rity mir rors . Shaving mirror , torch , dentists , → in solar furnace . T.IS#tT9T72IT!

④ # Sign - convention :- o Pole is origin . is a- anis ° Principal axis MIRROR FORMULA F origin T n-an.is •* - - ÷ ut ft+ T IT [with sign) f- a- coordinate of focus ✓ n- coordinate of image u se- coordinate of object Magnification (m) : Gives the relative extent to which the image of an object is magnified with respect to object size. *• hz - height of Ium= - = he - Image ho ho = height of Object MII An object is placed at a distance of 12cm in front of a concave ④Bmirror . It forms a real imag efrofmoutrhetimmeirsrolra.rg e r than the object . Calculate of image the dista nce → units# I obtect Trick :- IIIT Image - \" invested\" same- same Is FromRO VO =( pm = -ve → inverted . RI Invested ? i. • UT VI - ro re m=Il f RO IsVI Erect ro . R2 - zf gift at # (Trickett HHT 311Mt D solution () or Givens. v= -12cm as we know obtect is always on left so -resign) m- 4 times [but m tt sign? ? ] - object B \"Sayyed \" : Ro . 359 net trick that suit I as → . 4 given R I. . invested ! R 4O. . R I. . → same - same and we know for inverted , m- ⑦Ve - =

#27thTaete, Ptht isTrnicokted ⑤ Red pen part rough % m= y- f. )for boards , because ifas, m= IuTo = -4 4¥µ=-548c4m_ LII An object is placed at a distance of 8cm from a convex mirror of focal length 12cm . Find position of image . set: giveng E - 8cm f- I ? f- = +12cm feat ,s¥qn)using mirror formula, f- f- f- = If v at sign A #* iet nth ro automatically HII , ÷¥= 's f- = # + ¥ #E f ÷- , H-48cm_ - . cmhaendgiueminispactahlleodf REFRACTION it medium to another a elfigrahctt orna yo as passes from one gh R i f l i t . , l ' y l p o - ll l' denser rarer T T fer) Tx' ' > denser T- - Li )>r , rarer µ - i- . :8 - . - i - - . :' .. .. lightwhen from denser wtohernarelrighmtedraiuym g, oiets denser gboeensdsfrotomwarradrsetrheto bends away rays from normal . medium it normal . Cause of Refraction ?,beSnoi→.de, s.wAhtmoseownrwealerigdinhsktnthroeaewnrtenerorssrpmemaaeeldddiaeounnmfdsewlraihgnmehdnetdicituiosmmedp,niafitftreeastrriesvenlty ifferent media in d denser medium . less in reduces and it speed rarer medium gits speed increases .and it bends away from the normal .

⑥ # Refraction through a Rectangular Glass slab or E- angle of incidence Rarer F- angle of refraction T e- angle of emergence Denker - . ° AIfnglteheofinicnicdiednetncraey=faAllnsglenoorfmemalelyrgteoncteh,eLsEurfLacee ° of glass slab , then there is no bending of ray ti of light ii. e. it goes straight. rarer # LAWS OF REFRACTION : '% rtinraactniiodspeoanfrtesnsiatnyem,oetfhdieaanrgealeftratohcfetienpdcoidirneantycoeafntoidncttihhdeeennscoienr,emaoalfll to the interface of The planelie in the same . two The angle of refraction for light of given colour is constant for a given pair of media (Snell 's law) . sayingItis expressed as ' = At constant flu→ refractive index) # Refractive Index : The ex ten texopf recshsaend g e in direc t ion that take s place in a given ia is i pair of med in terms of refractive ndex . g. Nz represents refractive index of medium 2 with respect to medium Ig when light is going from medium L to medium 2 . i. ME HE = ssipnni ° The refractive index of a medium with respect to vacuum is called absolute refractive index , fight it that Faf of medium . tw . 8. VacKum ⑨ for glam / water pair Hg = AMI w all w et II 's ] ° It question is related to speed : race um lair |M=frg#legouftgroffpigghntinnai.cnfor egg in , → speed of light - speed of light in medium @ate) , IMwa ang - Ey- on - - -

⑦ LE: calculate angle of incidence of light ray incident on surface of a angle Sd: plastic slab of refractive index B g Tf of refraction is 30? given Lrair . - 30 ,- ,④ # glass, light is going from air to glass STA speed given ett af \"speed\" to aMg=,Mu8_a= ginning 4TH formula 4TH \"sin\" att l t zinnias iz - - SPHERICAL LENS sin i = I 2 %lE=6O°# A transparent material bound by two surfaces got which both surfaces are spherical, forms a lens . Thick at middle Thin at middle ←y th He convey converging dens concave/Diverging lens k3④ Lens k¥4# ¥ ? , of spheres of Isis *at Sai BEI Htt .. El ( Just an imeaasgiilnya)tion for solving aa questions → sphere ° Centre of Curvature Cc) : A lens has two spherical surfaces . Each surface forms a part of a sphere . The centre of these spheres are called centre of curvature ( 34T Cs 4G ) for Zfs & 2 Fa) . ° Principal Acuxrivsatu: reAnoimf aagleinnasryisstrcaailglehdt line passing through the two Axis centres of its principal . ° Optical centre lo) : Central point of a lens is called optical centre . ° Aperture : Effective diameter of the circular outline of a spherical lens is called its aperture . ° Principal focus If) : The point where the rays parallel to principal axis after

⑧ refraction meet is called principal focus . A lens has two principal foci. o focal length If ) : The distance of principal focus from optical centre . RAY DIAGRAMS # Rules: which are parallel to principal 9 Rays axis after ° , refraction will pass through principal focus in > F• >\" case of convex lens and will appear to becoming Iz principalfrom focus in lens F, o \" . soft o.ro - s ;r o case of concave ° Ray passing through or directed to the focus i will emerge parallel to principal axis . '> ' - - Es o 'Fez o Ray directed to optical centre will emerge , > out vndeviated . F-L o .fr Es TE ' # Image formation byconrentens.gg ' object → at infinity image → At Fz • a & diminished 2a Nature → Real , inverted Fs meeeanngmfs.ttobject → Beyond zf, → E double Ls image → between Fz and 2fz - nature real , inverted oldiminished za object → At zf, image → At Zfz ss 4 same size as of object . nature - Real gin rested ll -z object → Between hand 2A image ? Beyond 2Ez nature → Realginrerted 4 magnified.

⑨ Object - Atf image → at infinity 'l z z nature → Real , inverted 4 magnified . object - Between dens and Fs objectimage → On same side of lens as virtual and , magnifiedi z - nature - erect . # Image formation by concave lens 's. Lens Formula f- - f- =¥ sign convention is same as that for mirrors . T fy Also In convex lens focal lengths ⑦ ve (with sign) , and in concave - ore -|m=hh1÷=Y- hi - height of image - no - height of object - # if fpg ⑨- tfk3BdensyTHt applicable # POWER of LENSLP) : or diverge light rays is called Ability lens to converge Ofa fsfocallengthin metre power of the p=L_ dens . Flinn) SI unit ID) (called Dioptre - Lmg - fogyPower converters → ④ re of\" → ⑦ re → concave lens - ① re - If → ore

④ →0 . LIE A 5cm tall object is placed perpendicular to principal axis of a corner dens of focal length 20cm . Distance of object from lens is 30cm find position , nature and size of Image . Also find . power of lens hire ng . Yo IczmocmSok:- placedalwaysCo: object is on left) ! )t: convex → f- ⑦re f = -120cm using lens formula, f- - = To HIM m=h÷= F Q →lhi=t0cmq magnification → sign -0 re so tf = inverted ( HBO )by #, inverted means Roo . R. z i.e. Game - same) As magnitude of magnification is : Real Image o. increased so magnified Hence image is real ginrested and magnified. , Now, ¥mP = , ¥000 5¥