Geometrical Optics Questions and Answers

In the situation shown slab is close to the lens The distance in cm between the lens the mirror so that final image of object is formed on object itself may be 0 A 83 f 30cm 90 cm 00 B 87 R 40 cm 6cm H 3 2 C 85 D 86

e kg s 1 d kg s 36 A concave mirror of focal length f is placed at a distance of d from a convex lens of focal length f A beam of light coming from infinity and falling on this convex lens concave mirror combination returns to infinity The distance d must equal a f f b f f e 2f f d 2f f 37 A geostationary satellite is orbiting the earth at a height of 5R above that surface of the earth R being the radius of the earth The time period of another satellite in hours at a height gis at a An C in th Bro a Th gi

A convex lens of focal length 100 cm and a concave lens of focal length 10 cm are placed coaxially at a separation of 90 cm If a parallel beam of light is incident on convex lens then after passing through the two lenses the beam 1 Converges 2 Diverges 3 Remains parallel

and MP PMT 1996 2003 JIPMER 2000 Gujarat 200 b 1 d 1 1 a 1 u c u 1 i 3 is incident A ray of light travelling in the direction 2 on a plane mirror After reflection it travels along the direction 3j The angle of incidence is JEE Advanced 2013 a 30 c 60 b 45 d 75 1 c 60 1 Light trave refractive time take CBS t a c nc n

If radii of curvature of both convex surfaces is 20 cm then focal length of the lens for an object placed in air in the given arrangement is 10 cm 40 cm M 1 10000 www 200 1H 4 3 M 1 5 2 20 cm 4 80 cm

3 Width of a slab is 6 cm whose u If its rear surface is silvered and object is placed at a distance 28 c 2 from the front face Calculate the final position of the image from the silvered surface

Question No 22 Two planoconvex lenses each of focal length 10 cm refractive index are placed as shown In the space 2 left water R I 4 3 is filled The whole arrangement is in air The optical power of the system is in diopters

For what distance ray optics is a good approximation when the aperture is 4 mm and the wavelength of light is 400 nm A B D 24 m 40 m 18 m 30 m

24 Match the column I with column II option from the given codes Column I Column II i Planar wavefront incident P After reflection of on a thin convex lens refraction planar wave placed in air ii Planar wavefront incident 9 Spherical wavefront on a prism placed in air incidence side having centre towards incident side iii Planar wavefront incident r on a concave mirror of small aperture iv Planar wavefront incident S on convex mirror Codes nark a i p ii r iii s iv q b i q ii p iii r iv s c i r ii p iii q iv r Spherical wavefront having centre on other side Planar wavefront parallel to incident wavefront

Two plano convex lenses L 1 4 and L2 H2 1 5 of equal radii of curvature R 20 cm are placed so that their principal axes are parallel to each other and separated by distance of 4 5 mm as shown in figure A parallel beam of light is made to incident on L parallel to the principal axis a achal A R 20 cm 4 M 1 4 a gaan du 4 H 1 5 34R ZU ug yg za quiaz am fa zeng ugurz gach feu A ZA 4 5 mm 1 Uchle Yg A4 d c gw 3 4 DR 21 9 fa u 4 5 mm PA of L A f 4 5 mm D Final image is B Final image is f u 200 9 200 9 Correct Answer 100 9 100 9 PA of L cm from lens cm cm from lens cm C Final image is 2 5 mm below the principal axis of L 2 5 mm Correct Answer Final image is 2 mm below the principal

A ray of light is incident on a sphere of glass 1 414 at an angle of incident i as shown in figure For what value of i the ray will suffer total internal reflection inside the sphere i incident ray

As you walk away from a vertical plane mirror your image in the mirror is always the same height O decreases in height O changes from being a virtual image to a real image as you pass the focal point Omay or may not decrease in height depending on where the observer is positioned O is always a real image no matter how far you are from the mirror

To shoot a fish with a laser gun should you aim directly at the image slightly above or slightly below C b na a aim directly at the image b aim slightly above c aim slightly below

A thin convex lens whose focal length in air known to be 30 cm is cut into two parts by a transverse plane parallel to the principal axis 0 5 cm and 0 5 cm above the principal axis They are placed on the x axis as shown in the figure A point object is placed at the origin of a coordi nate system Find the co ordinates of the final image formed due to the rays which get refracted by both the parts of lens assuming paraxial ray approximations to be valid Origin 0 0 45 0 105 0 X

ALLEN A man with normal near point 25 cm reads a 4 book with small print using a magnifying glass a thin convex lens of focal length 5 cm What is the closest and the farthest distance at which he should keep the lens from the page so that he can read the book when viewing through the magnifying glass 1 4 8 cm 5 2 cm 2 4 2 cm 5 cm 3 6 2 cm 8 cm 4 9 cm 2 9 cm 4ch 1412 Fach face 25 alellufth uch ed alt fara allell fanda and 1 4 8 cm 5 2 cm 2 4 2 cm 5 cm 3 6 2 cm 8 cm 4 9 cm 2 9 cm a for a c

ALLEN When the angle of incidence on a material is 60 22 the reflected light is completely polarized The velocity of the refracted ray inside the material is in ms 1 3 10 2 3 3 x 108 4 0 5 10 2 108 fant at quaffa Stebri quia gard et sa sa ms 1 3 10 3 3 x 108 4 0 5 108 2 10

A convex lens of focal length 25 cm is placed at a distance x from a concave lens of focal length 7 cm When a parallel beam is incident on the convex lens it emerges as a parallel beam out of the concave lens What is the value of x Options 20 cm 18 cm 25 cm 32 cm

Two glass hem heres of refractive index and radius R are placed with their plane surfaces opposed separated by a distance d Answer A B C D Your Attempt Correct answer Rate this question If the combination is achromatic for rays parallel to the axis when their planes surfaces are facing towards each other then the value of d R 1 If the combination is achromatic for rays parallel to the axis when their planes surfaces are 2R facing towards each other then the value of d 1 If the combination is achromatic for rays parallel to the axis when their curved surfaces are R facing towards each other then the value of d 1 If the combination is achromatic for rays parallel to the axis when their curved surfaces are facing towards each other then the value of d R 2 1 1

Lx 15 cm A concave mirror is moving with velocity 41 2jcms whereas a point object is moving with 8 11 cms as shown in 1 figure The object is at a distance of 15 cm in front of mirror whose focal length is 10 cm The axial velocity of image is v then 4 x n find the value of n V 1 ych udda yu 41 2jcms ych farg azg faa seg gymz 81 11 cms r 1 a ad du w Mi J 15 cm V 4 fria gaf 10 cm 42 1 ffa xn 33

3 0 02 cm 4 0 cm Two point white dots are 1 mm apart on a black 15 paper They are viewed by eye of pupil diameter 3 mm Approximately what is the maximum distance at which these dots can be resolved by the eye Take wavelength of light 500 nm 1 6 m 2 3 m 3 5 m 4 Im 3 0 02 cm 4 0cm and a vad far 1 fast af 42 21 3 3 ft af alta dan alat di I i for at fang faf 500 nm 1 6 m 2 3 m 3 5m 4 Im

ALLEN A vessel is quarter filled with a liquid of refractive 41 index The remaining parts of the vessel is filled with an immiscible liquid of refractive index 3 2 The apparent depth of the vessel is 50 of the actual depth The value of u is 1 1 2 3 2 3 2 3 4 4 3 One of the refracting surfaces of a prism of angle 42 RT 1 4 T 3 2 and on 50 1 1 30 2 3 2 af 3 2 3 4 4 3 Ham

A square wire of side 1 cm is placed perpendicular 9 to the principal axis of a concave mirror of focal length 15 cm at a distance of 20 cm The area enclosed by the image of the wire is 1 4 cm 2 9 cm 3 6 cm 4 8 cm AB and CD are two slabs The medium between the 10 1 of you arft van amint atd and made fort aber 1 4 cm 3 6 cm AB CD 15 20 3 starf 2 9 cm 4 8 cm

11 Interference monochromatic fringes are produced by light falling normally on wedge shaped film of cellophane whose refractive index is 1 4 The angle of wedge is 20 sec of an arc and distance between successive fringes is 0 25 cm Calculate wavelength of light 1 Point

Find the distance of final image from mirror Eye 1 18 cm 3 20 cm 6 cm 4 6 cm 4 8 cm 2 16 cm 4 14 cm 17 sta 1 18 cm 3 20 cm 1 6 cm cm 8 cm 2 16 cm 4 14 cm

1 1 5 R 10 cm What is focal length of this curved surface 1 3 4 Correct Answer 4 10 cm 5 cm 20 cm 30 cm

17 There is a small air bubble inside a glass sphere 1 5 of radius 10 cm The bubble is 40 cm below the surface and is viewed normally from the outside figure 18 W16 Find the apparent depth of the bubble t 10 I

A thin prism having refractive index 1 52 and 3 prism angle is 10 is combined with another prism having refractive index 1 72 This combination produces dispersion without deviation The refracting angle of second prism should be 1 3 2 7 22 3 4 4 8 A ray of light travelling in a transparent medium 4 1 52 3 10 fra 1 72 3dates and was seu f for faca fa for at for 1 3 3 4 2 7 22 4 8 s greff

given object O and mirror arrangement the velocity in m s of the image with respect to ground wil be All the velocities are given with respect to ground 15 m s 5 30 2 m s A 46 243 B 46 243 C 462 243 1 30 cm f 20 cm y

A ray of light passing from a denser medium to a rarer medium gets partially reflected and refracted The angle of reflection is rand that of refraction is r The reflected and refracted rays make an angle of 90 with each other The critical angle will be sin tanr tan 1 sinr sin tanr

A ray of light initially parallel to the principal axis of a convex lens after refraction Will pass parallel to principal axis Will pass through principal focus Will pass through centre of curvature of curved surface Will pass through a point on principal axis between optical centre and principal focus

13 A disc is placed on a surface of pond which has refractive index 5 3 A source of light is placed 4 m below the surface of liquid The minimum radius of disc needed so that light is not coming out is b 3 m d 4m a o c 6 m CBSE PMT 2001

The bottom of a container is made of an equi convex lens The focal length of the lens in air is 60 cm Now its lower surface is silvered The refractive index of the material of the lens is 1 5 Water is filled in the container to a depth 30 cm When an object is placed at a distance cm above the water surface on the principle axis of lens the final image of the object coincides with the object Find the value off given 4 3 object 30 cm

A light ray of wavelength 450 nm in air is incident on plane surface of a transparent medium at angle of incidence 60 As it enters it deviates by 15 towards normal The wavelength of light in the medium is O 450 nm O 367 nm O 551 nm O 313 nm hm

When we see an object the image formed on th retina is 1 real 3 erect virtual 4 None of these

If the speed of light in a vacuum is c what is the speed of light in a medium with an index of refraction of 2 00 4 00c O2 00c O C 0 50c

In terms of light which quantity remains constant regardless of the medium through which it travels Ofrequency O speed O amplitude wavelength

What is measured by the index of refraction of a medium O how much light changes speed when entering the medium O the magnitude of the angle of refraction O the ratio of the speed of light in a vacuum to the speed of light in the medium the change in angle as a ray of light enters a medium

Refer to the table In which medium does light travel the fastest Medium lens of human eye quartz crystal Pyrex glass Plexiglas plastic benzene zircon diamond Index of refraction 1 41 1 46 1 47 1 51 1 50 1 92 2 42 The speed of light is the same in all media Olens of a human eye O diamond Obenzene

Which of the following does not illustrate a feasible method of altering the orientation of an image produced from an object or another image by using a prism a Image 1 c Image 1 p Image 2 Image 2 Object d Object Q Image Image bas

6 Draw the image in the following mirror I

A submarine is 300 m horizontally out from the shore and 100 m beneath the surface of the water A laser beam is sent from the submarine so that it strikes the surface of the water at a point 200 m from the shore If the outgoing beam from the surface of the water just strikes the top of building standing vertically at shore then the height of the building m u 4 3 is

The sketch shows a dummy lens with two principal rays of light refracted from the lens The dashed line is optical axis of the lens Which lens is it Optical axis Converging Lens More information is needed

mathongo mathongo A ray of laser of a wavelength 630 nm is incident at an angle of 30 at the diamond air interface It is go mathongo mathongo mathongo going from diamond to air The refractive index of mathongo mathongo mathongo mathongo mathongo mathongo diamond is 2 42 and that of air is 1 Choose the correct option co mathongo mathongo mathongo 1 angle of refraction is 24 41go mathongo mathongo mathongo mathongo 2 angle of refraction is 30 3 refraction is not possible hongo mathongo mathongo mathongo mathongo 4 angle of refraction is 53 4 mathongo mathongo thon mathongo mathongo mathongo mathongo mathongo mathoni nthon

An equiconvex lens of refractive index 3 2 and of radius of curvature 16 cm is placed co axially at a distance of 90 cm in front of concave mirror of radius of curvature 60 cm The surrounding medium is air A point object O is placed on the common axis of the lens and the mirror at a distance 90 cm left of the lens At an instant t 0 the object the lens and the mirror start moving with a speed 2 cm s 3 cm s and 8 cm s respectively in the direction shown in the figure If the time in sec after which the object and its final image coincide for the second time in sec is sec then final value of N 58 N 2 cm s 3 cm s 8 cm s Correct answer 05

A screen is placed 90 cm from an object The image of an object on the screen is formed by a convex lens at two different locations separated by 20 cm The focal length of the lens is A 18 cm B 21 4 cm D Correct Answer C 60 cm 85 6 cm

A ray of light falls on the surface of spherical glass 30 having refractive index n making angle 30 with normal then net angle of deviation between emergent and incident rays is 1 a 30 2sin 2n c 60 2 sin 1 b zero d 30 8 sin 11

5 Consider the situation in figure A small fish F is moving in vertically upward diection with velocity 8 cm s If the time dependent refractive index of water is u t t is in sec then velocity 4 t 3 3 in cm sec of fish as seen from above at t 0 sec is Consider upward direction as positive att 0 8 cm s LL T 16cm M0012 23 8 6 Vapp a d

35 180 A ray of light incident at 30 on a prism of refractive angle 90 The emergent ray is at an angle of 30 with the incider ray The value of angle of emergence will be 45 X 30 90 60

In the figure shown if the object O moves towards the plane mirror then the image I which is formed after successive reflections from M M respectively will move M O A towards right M Correct Answer Your Answer

A fish is raising vertically to the surface of water in a lake uniformly at the rate of 2 ms observes a bird diving vertically towards the water at a rate 4 ms vertically a it The refractive index of water is 4 3 The actual velocity of the bird is A 3 2 B 2 3 C 4 3 D