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Em, in, Apparent, Position, , of Light, , Electromagnetic, , Light, , es, , Properties, , is the form of energy that enables us to see., , wave, so does not require any medium to travel., , tends to travel in straight line., casts shadow., , Speed of light is maximum in vaccum. Its value is, , 3, , tC, , Light has dual nature i.e., wave as well as particle., , Light, , ss, , la, , ss, , Light, , Light, , la, , es, , Chapter -10, , C, , x 10 ms', , (a), , en, , When light falls on a surface, following may happen, , Reflection, , (c), , Absorption, , REFLECTION, , Em, in, , (b) Refraction, , Bouncing back of light when it strikes on a polished surface like mirror., , Laws, , of Reflection:, , (1) Angle of incidence is equal to the angle of reflection., (2) The incident ray, the reflected ray and the normal at the point of incidence,, all lie in the same plane., Normal, , Reflected ray, , Science Class, , es, , of Reflection, , 10, , ss, , Angle, , la, , ss, , es, , Angle of Incidence «, , C, , Incident Ray, , la, , C, , Page 1 of 23

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Em, in, Image: It is a point where atleast two light rays actually meet or appear to, meet., , Virtual Image, , Real Image, meet., , Canbe obtained on sereen., , es, , Inverted, E.g., image formed on cinema, , ss, , Image Formed by Plane Mirror, Plane mirror, , Object, , Image, , (i), (ii), , en, , Characteristics of Image, , tC, , B, , D, , la, , A, , la, , ss, , Screen., , Formed when light rays appear to, meet, Can'tbe obtained on screen., Erect, E.g., image formed by plane mirror, or convex mirror., , es, , Formedwhen light rays actually, , C, , Virtual and erect., Size of image is equal to the size of object., , Em, in, , (ii) Image is formed as far behind the mirror as the object is in front of it., (iv) Laterally inverted., Lateral Inversion: The right side of the object appears left side of the image, and vice-versa., Application of lateral inversion The word AMBULANCE is written as, aOMAJUaMA SO that it can be read correctly in rear view mirror of vehicles going, in front ofit., Spherical Mirrors : Mirrors whose reflecting surface is curved., Convex Mirror, Concave Mirror, , Reflecting, surface, , la, , ss, , Science Class 10, , C, , ss, , es, , Reflecting, surface, , Concave Mirror, , es, , Convex Mirror, , la, , C, , Page 2 of 23

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Em, in, Reflecting surface is curved outwards., , Divergingmirror, , *, , Reflecting surface is curved inwards., , Converging mirror, M, , la, , ss, , Principal, axis: The line joining the pole and center of curvature., Pole (P): The centre ofthe spherical mirror., Aperture (MN) : It is the effective diameter of the spherical mirror., Center of Curvature (C) : The centre of the hollow glass sphere of, which the mirror was a part., Radius of Curvature (R): The distance between the pole and the centre, of curvature., Focus (F): The point on principal axis where all the parallel light rays, actually meet or appear to meet after reflection., Focal length (): The distance between the pole and the focus., , es, , N, , between, , ture, , focal length and radius of curva, , Em, in, , Relationship, , en, , tC, , la, , ss, , es, , Principal axis, , C, , f, , Rules for making, )Aray, , ray diagrams, , by concave mirror, , parallel to the principal axis will pass through the principal focus,, after reflection., M, , N, , ss, , 145, , la, , Science Class 10, , es, , Aray passing through the principal focus of concave mirror will emerge, parallel to principal axis after reflection., , C, , ss, , es, , ii), , la, , C, , Page 3 of 23

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Em, in, P, , C, , P, , en, , When object is at intfinity:, , Image, , Em, in, , Parallel rays from A, object at infinity, , Position- At F', , A-, , D, , Nature, Size, , B, , is, , for images formed by concave mirror, , Ray diagrams, (i), , F, , of a concave mirror, , tC, , la, , (iv) Aray incident obliquely to the principal axis, reflected obliquely making equal angle., , ss, , es, , ray., , la, , ss, , es, , (ii) A ray of light passing through the centre of curvature of a concave, mirror is reflected back along the same path as it is a normally incident, , C, , -, , Real, inverted, , Point sized or highly, , diminished, , Image, , M, , (ii), , Image, , When object is beyond 'C', D, , Object, B, , Position-Between FF and 'C, Nature- Real, inverted, Size, , Image, , -, , Diminished, , es, , -, , 10, , ss, , Science Class, , la, , ss, , 146, , C, , es, , M, , la, , C, , Page 4 of 23

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Em, in, (i), , When object is at, , C, , Image, , Position-At 'C', Nature, , D, , Object, , --, , es, , E, Image, , (iv) When object is placed between F' and 'C°, M, , Nature, B, , P, , F, , ()When, , object is placed at 'F', , Image, , M, , Position, Nature, , Em, in, D, , Size, , FÖbject, , -, , -, , -, , At Infinity, , Real, inverted, , Highly enlarged, , B, , C, , H, , Size Enlarged, , en, , M, , Real, inverted, , -, , tC, , --lobiectiF, , B, , Beyond 'C, , Position, , A, , ss, , A', , la, , ss, , es, , Image, , P, , Same size as that of, , object, , la, , BC, , Real, inverted, , -, , Size, , B, , C, , Imageat, infinity, , M', , (vi) When object is between P' and F, , D, , Image, , F, , P, , B, , Nature, Size, , Obj ect, C, , Image, , Position- Behind the mirror, , M, , -, , -, , Virtual, erect, , Enlarged, , B', , es, ss, , 147, , la, , Science Class 10, , C, , ss, , es, , M, , la, , C, , Page 5 of 23

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Em, in, Uses of Concave Mirror, , es, , Concave mirrors are used by dentists to see large image of teeth of, patients. (Teeth have to be placed between pole and focus)., , la, tC, , la, , ss, , ii), , Used in torches, search lights and vehicles headlights to get powerful, parallel beam of light., , ss, , es, , i), , C, , (ii) Concave mirror is used as shaving mirror to see a larger image of the, , by Convex Mirror, Aray of light parallel to the principal axis of a convex mirror appear to, , Rule for image formation, (i), , en, , face., (iv) Large concave mirrors are used to concentrate sunlight to produce heat, in solar furnace., , Em, in, , diverge from the principal focus., , ii) A ray which is directed towards the focus of the convex mirror wil, , es, , -, , 10, , ss, , Science Class, , la, , ss, , 148, , C, , es, , emerge parallel to the principal axis after reflection., , la, , C, , Page 6 of 23

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Em, in, (iii) A ray directed towards the center of curvature of a convex mirror is, reflected back along the same., , es, , es, , PE, , ss, of images formed by convex mirror, , When object is placed at infinity:, , ), , Image, , la, , Ray diagrams, , tC, , la, , ss, , (iv) A ray incident obliquely to the principal axis is reflected obliquely., , C, , Position -At F*, , en, , Natureirtual, erect, Sizdeint sized, , ii), , Em, in, , P, , When objeet is placed between pole and infinity:, , Position, , Image, , Between, , P, , and 'F", , Natureirtual, erect, SizDiminished, , B, , A full length image, , B'F, , C, , of a tall building/tree can be, , seen in a small convex, , mirror., , Uses of Convex Mirror, 10, , 149, , ss, , -, , la, , Science Class, , es, , Convex mirrors are used as rear view mirrors in vehicles because, , C, , ss, , es, , 1), , la, , C, , Page 7 of 23

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Em, in, i), , Sign Convention for Reflection by Spherical Mirror, Or, New Cartesian Sign Convention, The object is placed to the left of the mirror., , ss, , ss, , es, , (ii) Convex mirrors are used at blind turns and on points of merging traffic, to facilitate vision of both side traffic., (ii) Used in shops as security mirror., , es, , (a) they always give an erect though diminished image., (b) they have a wider field of view as they are curved outwards., , la, , la, , (ii) All distances parallel to the principal axis are measured from the pole of, the mirror., , tC, , (iii) All distances mcasured in the direction of incident ray (along + X-axis), are taken as positive and those measured against the direction of incident, ray (along-X-axis) are taken as negative, , C, , en, , (iv) Distance measured perpendicular to and above the principal axis are, taken as positive., , Em, in, , (v) Distances measured perpendicular to and below the principal axis are, taken as negative., M, , (+ve), , Height upward|, ve), , ve), B, , +ve, , Por O, , X' B, , X, , Height downward, -ve), , length of concave mirror = Negative, , Focal, , length of convex mirror = Positive, , ss, , 10, , la, , Science Class, , es, , *u'is always negative., , Focal, , es, ss, , 150, , =, , C, , Object distance, , la, , C, , Page 8 of 23

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Em, in, Mirror Formula, , where, v = Image distance, u= Object distance, , of Spherical, , Mirrors, , ss, , It is the ratio of the height of image to the height of object., Height of image, , tC, , la, , Height of object, , la, , ss, , es, , es, , f=Focal length, , Magnification, , C, , Also,, , en, , m=-, , Em, in, , If 'm' is negative, image is real., If "m' is positive, image is virtual., Ifh,=h, then m = 1, ie., image is equal to object., Ifh,> h, then m> 1 i.e., image is enlarged., Ifh,<h, then m<1 i.e., image is diminished., Magnification of plane mirror is always + 1., +sign indicates virtual image., 1 indicates that image is equal to object's size., If 'm' is +ve' and less than 1, it is a convex mirror., Ifm' is tve' and more than 1, it is a concave mirror., If 'm' is 've', it is a concave mirror., , Check Your Knowledge, 1., , Magnification of plane mirror is +, , 2., , A real image, 1/5 th size of object is formed at a distance of 18 cm from, a mirror. What is the nature of the mirror? Calculate its focal length., -, , 10, , 151, , ss, , Science Class, , es, , What does it indicate?, , la, , 1., , C, , es, ss, , la, , C, , Page 9 of 23

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Em, in, 3. Name the type of mirror used in the following and reason for using it, , (a), , Solar furnace, , (b) Rear view mirror in a vehicle, 4. What should be the position, , (b) in torches as reflecting mirror?, , (a), , Define principal focus ofa spherical mirror., , (b) For what position of the object does a concave mirror form a real,, inverted and diminished image of the object? Draw the ray diagram., , An object 4 cm high is placed at a distance of 6 cm in front of a, concave mirror of focal length 12 cm. Find the position ofthe image., , la, , (c), , For what position of an object, a concave mirror forms a real image equal, to size of object?, , 7., , Identify the nature of mirror and mention two characteristics of image, formed when magnification m =+6., , 8., , Suggest a method to find approximate focal length of a concave mirror., , 9., , Draw ray diagram when, (a), , en, , tC, , 6., , Em, in, , la, , as a shaving mirror?, , es, , ss, , 5., , ofthe object, when a concave mirror is used:, , ss, , es, , (a), , C, , object is placed between pole and focus of a concave mirror., , (b) object is placed at infinity from a convex mirror., 10. Name the type, , (a), , of spherical mirror which, , has positive focal length., , (b) always forms a virtual image., , REFRACTION, Bending of light when it enters obliquely from one transparent medium to, another., Speed of light is maximum in vaccum. It is 3 x 108 m/s., Cause of refraction : Change in speed of light., , es, , -, , 10, , ss, , Science Class, , la, , ss, , 152, , C, , es, , Some examples ofrefraction:, The bottom of swimming pool appears higher., , la, , C, , Page 10 of 23

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Em, in, , es, ss, , ii), , Lemons placed in a glass tumbler appear bigger., , (iv) Letters of a book appear to be raised when seen through a glass slab., , Refraction, , through, , la, , la, , ss, , es, , (ii) A pencil partially immersed in water appears to be bent at the, interface of water and air., , glass slab, Incident Ray, , tC, , Normal, , Refracted Ray, , C, , air, , Glass, , Em, in, , en, , --, , d=Lateral, displacement, , Emergent Ray, , extent of bending of ray of light at the opposite parallel faces of, The, rectangular glass slab is equal and opposite, so the ray emerges parallel, to incident ray., Lateral displacement depends on, (a), , Refractive index of glass slab, , b), , Thickness of the glass slab, , Laws of Refraction, , es, , 10, , 153, , ss, , -, , la, , Science Class, , C, , ss, , es, , i) The incident ray, the refracted ray and the normal to the interface of two, transparent media at the point of incidence, all lie in the sameplane., , la, , C, , Page 11 of 23

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Em, in, (ii) Snell's law: The ratio of sine of angle of incidence to the sine of angle of, refraction is a constant, for a light of given colour and for a given pair of, media., sin i, Sin, , Constant, r, , es, , Velocity of light in medium1, , Velocity of light in medium 2, , ss, , ss, , n,, means refractive index of second medium with respect to first medium, and, , la, , la, , 2, , n,, , es, , Refractive index (7): The ratio of speed of light in a given pair of media, , means refractive index of first medium with respect to second medium., , tC, , 2, , C, , n=, , x 10, , (c=3, , en, , Absolute Refractive Index : Refractive index of a medium with respect, to vaccum or air., , ms), , Em, in, , Refractive index of one medium is reciprocal of other's refractive index, in a given pair., h2, , If refractive index of medium, , I, , w.r.t. air is given as, , n", and, , If refractive index of medium 2 w.r.t. air is given as ,n, Then, refractive index of medium, , 1, , w.r.t. medium 2, , ir, , n", , Refractive index of diamond is the highest till date. It is 2.42. It means, speed of light is, , 2.42, , times less in diamond than in vaccum., , es, , -, , 10, , ss, , Science Class, , la, , ss, , 154, , C, , es, , Optically denser medium : Out of two given media, the medium with, higher value of refractive index., , la, , C, , Page 12 of 23

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Em, in, Optically rarer medium: Out of two given media, the medium with, lower value of refractive index., When light enters obliquely from a rarer to a denser medium, it bends, towards the normal, Normal, , es, ss, , Denser, , When light enters obliquely from denser to a rarer medium, it bends, away from the normal., , la, , Normal, , la, , ss, , es, , Rarer, , tC, , Denser, , C, , Rarer, , index of a medium does not depend on physical density., , en, , Refractive, , Spherical lens: A transparent medium bound by two surfaces, of which one, or both surfaces are curved., , Concave lens, Thick from corners, , Thin from corners, , Thin, , Thick at center, , Plano, , Biconcave, , Convex, , Science Class 10, , es, , Biconvex, , 155, , ss, , ss, , es, , Plano, convex, , Diverging, , la, , Converging, , at centre, , C, , Convex lens, , Em, in, , Spherical lens, , la, , C, , Page 13 of 23

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Em, in, Rules for image formation by convex lens, A ray of light parallel to principal axis of a convex lens always pass, through the focus on the other side of the lens., , 2F2, , es, , Fi, , ss, , F, , O, , la, , 2F, , 2F2, , tC, , la, , ss, , (ii) A ray of light passing through the principal focus will emerge parallel, to principal axis after refraction., , es, , (i), , C, , 2F, , Nature, , Parallel, from, top rays, , Size Point sized or highly, diminished, , point, offobject, , of, B, , F2, , F, , Science Class 10, , es, , far, , Real, inverted, , ss, , ss, , 156, , 2F2, , la, , es, , B, , 2, , C, , A, , F, , of Imaged formed by Convex Lens, Image, When object is at infinity:, Position- At "F2, , Ray Diagrams, (), , Em, in, , en, , (1i) A ray of light passing through the optical center will emerge without, any deviation., , la, , C, , Page 14 of 23

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Em, in, 2F,, , Image, Position, B, , 2F, , Nature, Size, , es, , (iii) When object is at, , 2F, , -, , F,', , Real, inverted, , -, , Diminished, , Image, Nature Real,, , and, , Convex, lens, , -, , Same size, , 2F,, , Image, Position -Beyond 2F, Size, , 3, , Enlarged, , oF, , F, , B, , -, , tC, , Nature- Real, inverted, , object is at F,, Convex lens, , Image, , Em, in, , ()When, , Image (Real, inverted, and magnitfied), , en, , Object, , 2f, , Position At, Nature, , BI, , F, , Object, , la, , F', , Size, , inverted, , ss, , 2F2, , F, , (iv) When object is between, , 2F, , and 2F,, , Position- At *2F,, , la, , ss, , 2F, , Between, , es, , When object is beyond, , (ii), , C, , -, , Infinity, , Real, inverted, , Size- Highly enlarged, , C, , Rays, become, parallel, , Image, , at, , infinity, , f, (vi) When object is between 'F and optical centre, , Image, Position-On the same side of, the lens as object, Nature -Virtual and erect, Size Enlarged, On the basis of this position, this, lens is also known as magnifying, , es, , 157, , ss, , 10, , la, , Science Class, , C, , ss, , es, , lens., , la, , C, , Page 15 of 23

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Em, in, Rules for Image Formation, S.No Light ray, , by Concave Lenss, , Ray diagram, , How it appears after, , Parallel to, theprincipal, , es, , axis, , 3., , |, , ss, , on the same side of the lens, , After refraction from a, concave lens, the ray, appears to diverge from, the principal focus located, on the same side of the lens, , la, , Passing, through a, principal, focus, , F2, , Passing, through the, optical center, of a lens, , F2, , tC, , 2., , the principal focus located, , Em, in, , la, , ss, , F, , en, , ., , After refraction froma, concave lens, the ray, appears to diverge from, , es, , refraetion, , from object, is, , C, , After refraction from a, concave lens will, emerge without any, deviation, , Ray Diagrams of Images Formed by a Concave Lens, objectis placed at infinity: Image, )When, E, , Position-At, , F', , Natureirtual, erect, Sizdeint sized or highly, , es, , -, , 10, , ss, , Science Class, , la, , ss, , 158, , C, , es, , diminished, , la, , C, , Page 16 of 23

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Em, in, (ii) When object is placed between infinity and optical centre, , Position, , -, , Between F' and '0', , Naturdirtual, erect, SizdDiminished, , lenses, , for spherical, , conventions are similarto the one used for spherical mirrors, except, that measurements are taken from optical center of the lens., Focal length of convex lens = Positive, Focal length of concave lens = Negative, , ss, , Sign, , la, , la, , ss, , Sign convention, , es, , es, , F2, , Magnification:, m=Also,, , h, , =, , h,, , height of image, height of object, , Em, in, , h, , en, , tC, , Lens Formula:, , C, , m=, , Power of a lens:, , It is defined as the reciprocal of focal length in meter., , The degree of convergence or divergence of light rays is expressed in terms, of power, 1, , Power, , D, , m, , -, , 10, , meter, , es, , Science Class, , 159, , ss, , dioptre is the power of lens whose focal length is one, , la, , ss, , es, , 1, , 1, , =, , C, , 1D=, , P, , focal length (in meter), , SI unit of Power = dioptre, , la, , C, , Page 17 of 23

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Em, in, Power of convex lens, , Positive, , =, , Power of concave lens, , =, , Negative, , 1, , Power, , focal length or thickness, , a, , P-P, +P, + Pz..., , MARKER OBJECTIVE QUESTIONS, I. MULTIPLE CHOICE QUESTIONS, 1., Focal length of plane mirror is, b) Zero, a)At infinity, c) Negative, d) None ofthese, Image fornmed by plane mirror is, a) Real and erect, b) Real and inverted, d) Virtual and inverted, c)Virtual and erect, A concave mirror gives real, inverted and same size image if the object is, 3, placed, a)AtF, b)At infinity, d) BeyondC, c)AtC, Power of the lens is-40, its focal length is, 4., a) 4m, b)-40m, d) 25 m, c)-0.25m, A concave mirror gives virtual, erect and enlarged image of the object. The, position of theobject isa) At infinity, b) Between Fand C, d)AtF, c)Between Pand F, 6., In optics and object which has higher refractive index is calleda) Optically rarer, b)Optically denser, d) Refractive index, c)Optical dense, 7, The optical phenomena, twinkling of stars, is due to, a) Atmospheric reflection, b) Total relection, d) Total refraction, c)Atmospheric refraction, , ss, , la, , -, , 10, , ss, , Science Class, , la, , la, , ss, , 60, , C, , es, , ., , es, , Em, in, , en, , tC, , la, , ss, , 1, , es, , es, , Power of lens combination, , C, , C, , Page 18 of 23

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11., , Fill in the blanks:, (i) Image formed by a plane mirror is always., and.., (ii) A spherical mirror, whose reflecting surface is curved inwards, that is,, faces towards the centre of the sphere, is called, .. its radius of, (ii) The focal length of a spherical mirror is equal to, curvature., (iv) Speed oflight is ., (v) Lightrays always travels in., Answerin one word/one sentence., (i) Aconcave mirror produces three times magnified (enlarged) real image, ofan object placed at 10 cm in front ofit.Where is the image located?, (ii) The magnification produced by a plane mirror is +1. What does this, mean?, (ii) An object is placed at a distance of 10 cm from a convex mirror of focal, length 15 cm. Find the position and nature ofthe image., (iv) Define the principal focus of a concave mirror., Study the given ray diagrams and select the correct statement from the, , tC, , ., , la, , 1.a, 6.b, , la, , ss, , es, , 10., , ss, , 9., , Convex lens focus a real, point sized image at focus, the object is placeda) At focus, b) Between Fand 2F, d) At 2F, c)At infinity, The unitofpower of lens is, a) Metre, b) Centimeter, d) M-1, c)Diopter, curvature, The radius of, ofa mirror is 20cm the focal length isa) 20cm, b) 10cm, d) Scm, c)40cm, Answer, 2.c, 4.c, 5.c, 3.c, 10.b, 7.c, 8.c, 9.c, , es, , Em, in, 8., , C, , *****, , Em, in, , 12., , *, , en, , *******, , 13., , following, X, , 10, , 161, , ss, , Science Class, , es, , Screen, 25 cmL, , la, , Screen, , C, , ss, , es, , 20 cm, , la, , C, , Page 19 of 23

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Em, in, , ss, , la, , en, , tC, , la, , ss, , es, , lengths are 10 cm and 25 cm respectively., (C) Device X is a concave lens and device Y is a convex mirror, whose focal, lengths are 20 cm and25 cm respectively., D) Device X is a convex lens and device Y is a concave mirror, whose focal, (CBSE 2017), lengths are 20 cm and25 cmrespectively., 14. A student obtains a blurred image of distant object on a sereen using a, convex lens. To obtain a distinct image on the screen he should move the, lens., (A) away from the screen, (B) towards the screen, (C) toaposition very far away from the screen, (D) either towards or away from the screen depending upon the position of, the object., (CBSE 2017), 15. Assertion (A): The bottom of a tank or pond, filled with water appears to be, raised., , es, , (A) Device X is a concave mirror and device Y is a convex lens, whose, focal lengths are 20 cm and 25 cm respectively., (B) Device X is a convex lens and device Y is a concave mirror, whose focal, , C, , Em, in, , Reason (R): The apparent depth of the tank is given by 1/n times the original, depth., (a) (A)is incorrect and (R) is correct., (b) (A)is correct and (R) is incorrect., (c) Both (A) and (R) are correct but (R) is not the correct explanation of, (A)., , (d) Both (A) and (R) are correct but (R) is the correct explanation of (A)., 16. Assertion (A): The shaving mirrors are convex mirrors., Reason (R): Convex mirror always forms a virtual image., (a) (A) is incorrect and (R) is correct., , es, , -, , 10, , ss, , Science Class, , la, , ss, , 162, , C, , es, , (b) (A)is correct and (R) is incorrect., (c) Both (A) and (R) are correct but (R) is not the correct explanation of, (A)., (d) Both (A) and (R) are correct but (R) is the correet explanation of (A)., , la, , C, , Page 20 of 23

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Em, in, 3 Marker Questions, 1., , Refractive indices of medium A, B and Care 1.3, 1.5 and 1.4 respectively., In which of the following the speed of light will be the:, (a), , fastest, , a, , 4. A5 cm tall object is placed perpendicular to principal axis of convex, lens of focal length 10 cm. If the object is placed 30 cm away from the, lens, find the position, size and nature of image., 5. A ray travelling in water enters obliquely into glass. Does the light bend, towards or away from the normal and why ?, , ss, , Light enters from air to kerosene having a refractive index of 1.47. What, is the speed oflight in kerosene?, , la, , la, , ss, , 3., , es, , es, , (b) slowest and why?, 2. A compound lens is made up of two thin lenses having power + 12.5 D, and 2.5 D. Find the focal length and power ofthe combination., , tC, , 6. An object is placed at the focus of a convex lens. Draw ray diagram to, , C, , locate the position of image formed., , ., , es, , 163, , ss, , 10, , la, , Science Class, , C, , ss, , es, , Em, in, , en, , Ifthe image formed by a spherical mirror for all positions of the object placed in front, of it is always erect and diminished, what type of mirror is it? Draw a labelled ray, (CBSE 2018), diagram to support your answer, 8. State the laws of refraction of light. Explain the term 'absolute refractive index of a, medium' and write an expression to relate it with the speed of light in vacuum., (CBSE 2018), 9. What is meant by power of a lens? Write its SI unit. A student uses a lens of focal, length 40 em and another of-20 cm. Write the nature and power ofeach lens., (CBSE2018), 10. An object is placed at a distance of 15 em from a concave lens of focal length 30 cm., List four characteristic (nature, position, etc.) ofthe image formed by the lens., (CBSE 2017), 11. "A lens can form a magnified erect image as well as magnified inverted image of an, object placed in front of it". Same the nature of this lens and draw ray diagrams to, justify the above statement., (2017), Mark the position of 0, F and 2F in the diagram., 12. The refractive indices of glass and water with respect to air are 3/2 and 4/3, respectively. Ifspeed oflight in glass is 2 x 108 m/s, find the speed of light in water., (CBSE 2016), , la, , C, , Page 21 of 23

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Em, in, 5 Marker Questions, , One half of a convex lens is covered with black paper., , 1., , (a), , Show the formation of image of a object placed at 2F, of such, covered lens with the help of ray diagram. Mention the position and, nature of the image., , (b) Draw labelled diagram for each case., , (a), , What happens to a ray of light when it travels from one medium to, another having equal refractive indices ?, , la, , 3., , 4. (a), , Define, , power, , Why does a lemon kept in water in a glass tumbler appear to be, bigger than actual size?, , 1., , Object Distance-u(cm), -100, , +25, , 2., , -60, , +30, , 3., , -40, , +40, , 4., , -30, , +60, , -25, , 100, , 6., , -15, , +120, , 164, , Science Class, , -, , 10, , ss, , es, , ., , es, , Image Distance-v(cm), , la, , |S. No., , Em, in, , Analysis the following observation table showing variation of image, distance (v) with object distance (u) in case of a convex lens and answer the, questions that follow without doing any calculation:, , 5., , ss, , dioptre of power. Find the focal length of a lens of, 2.0 D., , 1, , en, , (b), , tC, , (b) State the cause of refraction of light., , C, , ss, , la, , Write the position of object in each case., , (a), , ss, , A thin converging lens forms a (i) real magnified image, (ii) virtual, magnified image., , 2., , la, , es, , es, , (b) Draw the ray diagram for same object at same position in front of, the same lens, but now uncovered. Will there be any difference in, image obtained in the two cases ? Give reasons for your answers, , C, , C, , Page 22 of 23

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b), c), , ss, , la, , la, , ss, , es, , 6., , What is the focal length of the convex lens? Give reason to justify your, answer., Write the serial number of the observation which is not correct. On what, basis have you arrived at this conclusion?, Select an approximate scale and draw a ray diagram for the observation at S., No.2Also findthe approximate value of magnification., (a) If the image formed by a mirror for all position of the object placed in, front of it is always diminished, erect and virtual, state the type of the mirror, and also draw a ray diagram to justify your answer. Write one use such, mirrors are put to and why., b) Define the radius of curvature of spherical mirror. Find the nature and, focal length of a spherical mirror whose radius of curvature is +24 cm., , No bending, , tC, , Hints to Long Answer Type Questions, 3. (a), , of light., , 1, , en, , (b) Change in refractive index of two medium., 4. (a), , es, , Em, in, a), , C, , dioptre: t is the power oflens whose focal length is, , 1, , m., , Em, in, , P, , Size, , Enlarged, , Nature, , Real and inverted, , ss, , Science Class, , 10, , 165, , ss, , At infinity, , la, , Image fornmed, , C, , Ray diagram., , es, , 6., , es, , (b) Due to refraction of light., , la, , C, , Page 23 of 23