Geometrical Optics Questions and Answers

In the arrangement shown in figure image of light source 0 is obtained at the bottom of beaker containing water Find value of H 3 f 30 cm 36 cm 100 cm 20 cm 45 H

Minimum deviation is observed with a prism having angle of prism A angle of deviation S angle of incidence i and angle of emergence e We then have generally i e i e i e i e

There is a plane mirror kept vertically at ground An object is kept in front of it at the distance d If the object moved 1cm towards the mirror and mirror moves 2cm away from object Find the distance and direction which the image of the object move edited 10 37 PM

A beam of light converges towards a point 10 cm behind a convex mirror of focal leng 20 cm Find the nature and position of image A 20 cm real erect B 10 cm virtual inverted C 15 cm real erect D 15 c virtual erect

An achromatic convergent doublet has power of 2D If power of convex lens is 5D then ratio of the dispersive powers of a convergent and divergent lenses will be a 3 5 b 2 5 c 2 3 d None of these

A beam of light converges to a point on a screen S A mirror is placed in front of the screen at a distance of 10 cm from the screen It is found that the beam now converges at a point 20cm in front of the mirror Find the focal length of the mirror A 10 cm B 20 cm C 30 cm D 40 cm

the A 18 cm A concave mirror gives a real image magnified 4 times When the object is moved 3 of the real image is 3 times Find the focal length of mirror B 24 cm C 36 cm D 48 cm magnification

A beam of light converges towards a point 30 cm behind a convex mirror of radius of curvature 40 cm Find the nature and position of image A 40 cm virtual inverted C 60 cm virtual inverted B 20 cm real inverted D 40 cm real erect

Sample Problem 16 A linear object of length 4 cm is laced at 30 cm from the plane surface of hemispherical glass of adius 10 cm The hemispherical glass is surrounded by water ind the final position and size of the image B a 5 3 cm A 4 cm 30 cm b 4 3 cm c 5 cm d 2 3 cm

3 100 C 4 Zero 23 Charge Q on capacitor varies with voltage Vas shown in the figure where Q is taken along the x axis and V along the y axis The energy stored in the capacitor when capacitor is charged to 3 C is 1 12 J VA 4 V 3 C 2 6 J Q

0 For two different positions of a thin convex lens between a real thin erect object and the screen the length of images formed are 18 cm and 8 cm o respectively The length of the object is 1 10 cm 2 12 cm 3 13 cm 4 14 cm

6 A monochromatic light beam is incident on a glass prism cross section of which is a regular hexagon Width of the beam is so adjusted that it falls up to middle of two adjacent sides of the prism as shown For what refractive index of glass two separate parallel beams emerge out M 1 33 ront qulinder of radius R and height H made from a materia

A meniscus lens have convex surface of curvature 20 cm and concave surface 30 cm If the lens is constructed of glass u 1 5 the focal length will be 1 4 cm 3 120 cm 2 4cm 4 120 cm l length

A luminious point is moving with speed Vo towards a spherical mirror along its axis then the speed a which the image of this point object is moving is given by 1 V Vo no 3 V Vo 2u R 2 V V 4 V R 2u R R 21 R 2

The nature of the image of a candle flame located 40 cm from a concave spherical mirror is real inverted and magnified four times Then the radius of curvature of the mirror is 1 32 cm 3 48 cm 2 64 cm 4 80 cm

A diffraction pattern is obtained by using beam of red light What will happen if red light is replaced by blue light Bands become broader and farther apart No change will take place Bands disappear Diffraction bands become narrow and crowded

A crown glass prism of angle 10 and dispersive power 0 01575 is to be combined with a flint glass prism of dispersive power 0 02764 If the refractive indices of the prism for sodium D light are respectively 1 511 and 1 621 calculate the net dispersion produced by the combination Ans 0 0607

a horizontal table and water is filled in it up to a height of 5 00 cm A small dust particle flotes on the water surface at a point P vertically above the point of contact of the mirror with the table The image of the dust particle as seen from a a point directly above It is 8 cm Find the value of a Use refractive index of water is 1 33 P

A right prism is to be made by selecting a proper material and the angles A and B B A It is desired that a ray of light incident normally on AB emerges parallel to the incident direction after two internal reflections a What should be the minimum refractive index for this to be possible b For uw 5 3 is it possible to achieve this with the angle A equal to 60 Ans a 2 b 37 A small angle prism and convex lens are arranged as shown in the figure Prism Lens

A light ray traveling in air is incident on one face of a right angle prism with an index of refraction n 1 50 as shown in this Figure and the ray follows the path shown in the figure Assuming 0 60 0 and the base of the prism is mirrored determine the angle o made by the outgoing ray with the normal to the right face of the prism Incoming ray Outgoing ray n Mirror base Fiqure P35 69

QThe convex surface of a thin concavo convex lens of glass 1 5 has a radius of curvature 20 cm The concave surface has a radius of curvature 40 cm The convex side is silvered and placed at horizontal surface The concave part is 4 The distance of a 3 filled with water pin above the horizontal surface where its image coincides with it is approx

Parallel light rays are falling on the plane surface of a semi cylinder made of glass at an angle of 45 in such a plane which is perpendicular to the axis of the semi cylinder Index of refraction is 2 Considering a maximum of two refractions find the angular spread of emerging rays from curved interface in degrees Sr Super60 All Space for rough work Page 9

A rod of glass 1 5 and of square cross section is bent into the shape shown in figure A parallel beam of light falls on the plane flat surface A as shown in figure If a is the width of a side and R is the radius of circular are then for what maximium value of light entering the glass slab through R surface A emerges from the glass through B 1 1 5 2 0 5 3 1 3 4 None of these

QA concave mirror has radius of curvature of 40cm It is at the bottom of a glass that has water filled up to 5cm see figure If a small particle is floating on the surface of water its image as seen from directly above the glass is at a distance d from the surface of water The value of dis close to Refractive index of water 1 33 particle 5cm

Numerical value type Questions An object is placed at a distance of 15cm from a convex lens of focal length 10cm on the other of the lens a convex mirror is placed at its focus such that the image formed by the combina coincides with the object itself The focal length of the convex mirror is cm

A glass slab has concave surface of radius of curvature 2 0 cm The glass has refractive index of 1 5 If a point object is placed on axis in air at a distance of 18 cm from concave face find the position and nature of the image

Water is filled in a container upto a height of 5cm There is a concave mirror of radius of curvature 40 cm A person just above the surface observes images of A The distance of image from water surface is water 1 33 A 5 cm

A ray incident on a plane mirror at angle i and produced a net deviation of 8 between incident ray and reflected ray Choose the correct graph between the deviation 8 and incident angle i 8 8 1 3 TJ2i 0 TU2 i 0 2 4 8 T 2 i 0 Medica Div 2 i 0

16 A spider is hanging above the north pole of a transparent globe diameter d at a distance d 3 from the centre of the globe Refracti index of the material of the globe is 2 Between which latitudes a can sit on the globe so that it cannot be seen by the spider Treat t spider and the fly both as point objects Betwen 60 N 60 s

The bottom of the beaker is silvered which contains water of refractive index upto a height 2H 4 3 A fish is at a height H from the bottom of the beaker At what distances from him of the fish its image appear to a man whose eyes are at a height H from the surface of water 1 bgel Isso 2H 10H 3 5H Aeye of man ATH H 2 4H 4H 3

35 A ray of light makes normal incidence on the diagonal face of a right angled prism as shown in figure If 9 3 37 then the angle of deviation is sin 37 1 53 2 106 air 5 53 5 5 air 2 127 4 90 Sin Sin 30

Example 9 30 A concave mirror of radius of curvature two metre is placed at the bottom of a tank of water The mirror forms an image of the sun when it is directly overhead Calculate the distance of the images from the mirror for i 160 cm and ii 80 cm of water in the tank Take for water 4

The image shown above is a O concave diverge concave converge convex converge convex diverge lens and it will cause light rays to

2 In a setup of displacement method experiment distance between the screen and a light source is 120 cm and the lens used has a small aperture By moving the lens between the source and the screen sharp images are obtained on the screen for two different positions of the lens The ratio of sizes of these two images is 1 9 a What is the focal length of the lens 22 5cm b Which image is the brighter one Determine the ratio of the brightness of these two images Smaller 9 times brighter

A small object is placed infront of arrangement shown Find distance of final image from the lens in cm 3 cm 1 5 Object f 10 cm 15 cm Lens 15 cm 10 cm Slab Mirror

1 A research submarine has a circular glass window in its bottom to observe the seabed Radius of the window is r 30 cm thickness of the glass is t 20 mm refractive index of water is w 1 25 and that of the glass is g 1 5 If the seabed is d 6 0 m beneath the window estimate radius of portion of the seabed visible through the window Y d u 8

A lens with a focal length of 20 cm is used to project an image onto a screen If the original object is 26 cm away from the lens how many cm from the lens will the image be Your Answer Answer Question 2 1

16 For a ray of light passing through prism which of the following statements is true in case of i and d O As i increases decreases continuously O As i increases increases continuously As i increases 8 decreases reaches minimum value and again it increases As i increases 8 increases reaches maximum value and again it decreases

A ray of light enters at grazing angle of incidence into an assembly by three isoscl right angled prisms having refractive indices 2 x and 3 3 If finally emerge light ray also emerges at grazing angle then x is H H H3

A biconvex thin lens is prepared from glass 1 5 the two bounding surfaces having equal radii of 25 cm each One of the surfaces is silvered from outside to make it reflecting An object is placed before this lens at distance 1 cm so that the image is formed on the object itself The value of 20 is Lens is placed in air u 1 5 C 25cm B 25cm C

Light passes from air into water How does the angle of incidence compare to the angle Incidence angle Refraction angle Incidence angle Refraction angle Incidence angle Refraction angle

of 10cm Find the total momentum delivered during 10 minutes time span 6 A thin double convex lens of focal length f is broken into two equal halves at the axis The two halves are combined as shown in figure What is the focal length of combination in ii Q ii

58 Suppose you have three concave mirrors A B and C of focal lengths 10 cm 15 cm and 20 cm or each concave mirror you perform the experiment of image formation for three values of object listance of 10 cm 20 cm and 30 cm Giving reason answer the following A For the three object distances identify the mirror mirrors which will form an image of magnification 1

In Young s double slit experiment if monochromatic light is replaced by white light 1 All bright fringes become white 2 All bright fringes have colours between violet and red 3 Only the central fringe is white all other fringes are coloured 4 No fringes are observed

Example 9 7 A magician during a show makes a glass lens with n 1 47 disappear in a trough of liquid What is the refractive index of the liquid Could the liquid be water Solution The refractive index of the liquid must be equal to 1 47 in order to make the lens disappear This means n n This gives 1 f 0 or f The lens in the liquid will act like a plane sheet of glass No the liquid

1 A coin 3 00 cm in diameter is embedded in a solid glass sphere of radius 40 0 cm The index of refraction of the sphere is 1 50 and the coin is at 30 0 cm from the surface of the sphere as shown in the figure below i Find the position of the image ii What is the magnification of the image 3 U coin CALASS 400m x 30cm M 1 S

29 Diameter of a plano convex lens is 6 cm and its thickness at the centre is 3 mm Then the focal length of the lens if the speed of light in the material of lens is 2 x 108 m s 1 7 5 cm 3 45 cm 2 15 cm 4 30 cm

A convex lens of focal length f is placed somewhere in between an object and a screen The distance between the object and the screen is x If the numerical value of the magnification produced by the lens is m then the focal length of the lens is 1 2 3 4 mx m 1 mx m 1 m 1 m X m 1 X

A object is placed at a distance of 1 5 m from screen and a convex lens is placed in betwee them which produces 4 times magnified imag on the screen Find the focal length and th position of lens from the object 1 f 0 24 m 0 6 m 2 f 0 375 m a 0 75 m 3 f 0 24 m 0 3 m 4 f 0 375 m 0 3 m

An object is placed closer to a converging lens than its focal length Can the image be projected onto a screen no because it will be a virtual image O yes because it will be a virtual image yes because it will be a real image no because it will be a real image