# Geometrical Optics Questions and Answers

Physics
Geometrical Optics
Assuming human pupil to have a radius of 0 25 cm and comfortable viewing distance of 25 cm the minimum separation between two objects that human eye can resolve at 500 nm wavelength is 100 m 1 m a c b 300 m d 30um
Physics
Geometrical Optics
An object 2 4 m in front of a lens forms a sharp image on a film 12 cm behind the lens A glass plate 1 cm thick of refractive index 1 50 is interposed between lens and film with its plane faces parallel to film At what distance from AIEEE 2012 lens should object shifted to be in sharp focus on film 1 7 2 m 2 2 4 m 3 3 2 m 4 5 6 m
Physics
Geometrical Optics
A transparent solid cylindrical rod has a refractive index of mid point of one end of the rod as shown in the figure front The incident angle 0 for which the light ray grazes along the wall of the rod is 3 2 1 sin 2 sin 2 3 3 sin It is surrounded by air A light ray is incident at the AIEEE 2009 1 3 4 siny 1
Physics
Geometrical Optics
A transparent cube contains a small air bubble Its apparent distance is 2 cm when seen through one face and 5 cm when seen through other face If the refractive index of the material of the cube is 1 5 the real length of the edge of cube must be 1 7 cm 2 7 5 cm 3 10 5 cm 14 cm
Physics
Geometrical Optics
Image formed on retina of eye is proportional to 1 size of object 2 area of object The phenomena of total internal reflectic size of object 3 size of image who 4 size of ima size of obj
Physics
Geometrical Optics
3 If Assertion is true 4 If Assertion Reason both are false In the figure a ray of light is perpendicular to the face AB of a glass prism u 1 52 Find the value of 0 so that the r is totally reflected at face AC if the prism is immersed in water u 1 33 Given sin 61 0 875
Physics
Geometrical Optics
A ray of light which is initially horizontal passes through a glass cylinder of radius R as shown in the figure given below Taking refractive index of air nair 1 based on the geometry of the light ray s path as shown in figure find index of refraction of the glass nglass horizontal ray R 60 C nglass nar 1 00 R Horizontal
Physics
Geometrical Optics
8 Measurement of focal length of a convex lens by putting an object at a distance u from the lens and v is th distance of real image from lens then the correct grap between y and u is 1 3 u t U 2 4 U u
Physics
Geometrical Optics
Which of the following statements is NOT correct A An object placed between f and 2f of a concave mirror produces a real image beyond 2f B An object placed between the pole and the focus of a concave mirror produces a virtual and enlarged image C A convex mirror always produces a virtual image independent of the location of the object D The virtual image produced by a convex mirror is erect and magnified
Physics
Geometrical Optics
113 The critical angle for total internal reflection of light going from medium I to medium II is given by the relation tan ic 5 9 The refractive index of the I medium with respect to the medium II is A 1 8 C 156 5 B 1 6 D 106 5
Physics
Geometrical Optics
19 If 0 and 0 be the apparent angles of dip observed in two vertical planes at right angles to each other then the true angle of dip 0 is given by 1 tan 0 tan 0 tan 0 2 cot 0 cot 0 cot 0 3 tan 0 tan 0 tan 02 4 cot 0 cot 0 cot 0 ma nics
Physics
Geometrical Optics
7 A lens having focal length fand aperture of diameter d forms an image of intensity I Aperture d of diameter in central region of 2 lens is covered by a black paper Focal length of lens and intensity of image now will be respectively 2010
Physics
Geometrical Optics
2 An unpolarised beam of light is incident on a group of four polarising sheets which are arranged in such a way that the characteristic direction of each polarising sheet makes an angle of 30 with that of the preceding sheet The percentage of incident light transmitted by the first polariser will be a 100 OS b 50 c 25 d 125
Physics
Geometrical Optics
A plano convex lens of refractive index 1 5 and radius of curvature 30 cm is silvered at the curved surface Now this lens had been used to form the image of an object At what distance from this lens an object should be placed in order to have a real image of the size of the object i 30 cm arafa for at O A 20cm B 30cm fafar and for fi fosen fafara C 60cm di 1 5 D 80cm tifo f
Physics
Geometrical Optics
Illustration 1 7 Show that the minimum size of a plane mirror required to see the full image of an observer is half the size of that observer Sol Let HF is the height of the man and E is the eye level Draw the rays HM and FM incident at the edges of the mirror Complete the ray diagram as shown in Fig 1 17 It is self explanatory if you consider lengths x and y as shown in the figure
Physics
Geometrical Optics
3 Become zero A beam of light composed of red and green rays is incident obliquely at a point on the face of a rectangular glass slab When coming out of the opposite parallel face the red and green rays emerge from AIPMT 2004 1 Two points propagating in two different non parallel directions 2 Two points propagating in two different parallel directions 3 One point propagating in two different directions 4 One point propagating in the same direction of ong kilometre from two objects
Physics
Geometrical Optics
angle of second prism should be 176 2 8 3 10 4 4 A beam of light from a souce L is incident normally on a plane mirror fixed at a certain distance x from the source The beam is reflected back as a spot on a scale placed just above the source L When the mirror is NEET 2017 rotated through a small angle 0 the spot of the light is found to move through a distance y on the scale The angle is given by
Physics
Geometrical Optics
A beam of light consisting of red green and blue colours is incident on a right angled prism The refractive index of the material of the prism for the above red green and blue wavelength are 1 39 1 44 and 1 47 respectivel The prism will NEET 2015 Blue Green Red 45 1 not separate the three colours at all 2 separate the red colour part from the green and blue colours 3 separate the blue colour part from the red and green colours 4 separate all the three colours from one another
Physics
Geometrical Optics
A astronomical telescope has objective and eyepiece of focal lengths 40 cm and 4 cm respectively To view an object 200 cm away from the objective the lenses must be separated by a distance 1 50 0 cm NEET 1 2016 2 54 0 cm 3 37 3 cm Th 4 46 0 cm VDSP in 1 Distance between two slits is d 52 where is the wavelength
Physics
Geometrical Optics
A microscope has an objective of focal length 0 5 cm and an eye piece of focal length 1 cm It is desired to have a magnification of 500 The length of the microscope tube required for this is A 10 cm B 15 cm C 20 cm D 25 cm
Physics
Geometrical Optics
the focal length of objective and eye lens of a stronomical telescope are respectively 2m and 5 cm Final image is formed at i least distance of distinct vision ii infinity The magnifying power in both cases will be 4 48 40 2 40 48 3 40 48 4 48 40 pouco
Physics
Geometrical Optics
A body is located on a wall Its image of equal size is to be obtained on a parallel wall with the help of a convex len The lens is placed at a distance d ahead of second wall then the required focal length will be AIPMT 2002 1 Only d 4 3 More than d but less than d 7 2 d 2 Only 2 4 Less than d
Physics
Geometrical Optics
A biconvex lens forms a real image of an object placed perpendicular to its principal axis Suppose the radii of curvature of the lens tend to infinity Then the image would 1 Disappear 2 Remain as real image still Be virtual and of the same size as the object 4 Suffer from aberrations
Physics
Geometrical Optics
In Gallilean telescope if the powers of an objective and eye lens are respectively 1 25 D and 20D then for rel vision the length and magnification will be 1 21 25 cm and 16 2 75 cm and 20 3 75 cm and 16 4 8 5 cm and 21 25
Physics
Geometrical Optics
1 20 cm 2 40 cm 3 30 cm 4 10 cm A luminous object is placed at a distance of 30 cm from a convex lens of focal length 20 cm On the other side of the lens at what distance from the lens must a convex mirror of radius of curvature 10 cm be placed in order to have and upright image of the object coincident with it 1 12 cm 2 30 cm fo plano 3 50 cm 4 60cm Convex lens of focal lenght f is silvered It will behave as
Physics
Geometrical Optics
The image for the converging beam after refraction through the curved surface is formed at n 1 n 3 2 30 R 20cm 1 x 40 cm 2 x 40 3 cm 40 3 3 x cm 180 7 4 x cm
Physics
Geometrical Optics
The refractive indedx of a prism for a deviation the angle of incidence will be 1 30 monochromatic wave is 2 and its refracting angle is 60 For minimum 2 45 3 60 4 75 of monochromatic light is incident at one surface of a equilateral prism Angle of incidence is 55 and
Physics
Geometrical Optics
In the figure given below there are two convex lens L and L having focal length of f and f respectively The distance between L and L will be 1 f 2 L 3 f f 4 f f
Physics
Geometrical Optics
deviation of 1 15 2 22 5 3 0 4 12 5 The refractive index of the material of prism of 60 angle is 2 At what angle the ray of light be incident on it so that minimum deviation takes place 45 emerging Cantive index of the material of the prism is 2 60 3 30 4 75 of light is incident at angle of 60 on one face of a prism which has an apex angle of 30 The ray mi
Physics
Geometrical Optics
The dispersion of light in a medium implies that 1 lights of different wavelengths travel with different speeds in the medium 2 lights of different frequencies travel with different speeds in the medium 3 the refractive index of medium is different for different wavelengths 4 all of the above angle of light passing from glass to air is minimum for
Physics
Geometrical Optics
1 2 4 2 1 5 3 1 2 A beam of light is converging towards a point A plane parallel plate of glass of thickness t refractive index u is introduced in the path of the beam The convergent point is shifted by assume near normal incidence 1 1 1 away 2 1 away 3 nearer 4 1 1 neare t
Physics
Geometrical Optics
4 It is totally reflected from all the three sides of prism and never emerges out When light rays are incident on a prism at an angle of 45 the minimum deviation is obtained If refractive index of the material of prism is 2 then the angle of prism will be 1 30 2 40 3 50 4 60 fronting angle is 60 For minimum
Physics
Geometrical Optics
The critical angle between an equilateral prism and air is 45 If the incident ray is perpendicular to the refracting surface then 1 After deviation it will emerge from the second refaracting sufrace 2 It is totally reflected on the second surface and emerges out perpendicularly from third surface in air 3 It is totally reflected from the second and third refracting surfaces and finally emerges out from the first surface 4 It is totally reflected from all the three sides of prism and never emerges out When light rays are incident on a prism at an angle of 45 the minimum deviation is obtained If refractive index of the
Physics
Geometrical Optics
A diver in a swimming pool wants to signal his distress to a person lying on the edge of the pool by flashing his water proof flash light 1 He must direct the beam vertically upwards 2 He has to direct the beam horizontally 3 He has to direct the beam at an angle to the vertical which is slightly less than the critical angle of incidence for total internal reflection 4 He has to direct the beam at an angle to the vertical which is slightly more than the critical angle of incidence for the total internal reflection dir 3500 and 7000 then the critical angle of x relative to y will be Tul
Physics
Geometrical Optics
3 Concave mirror The field of view is maximum for 4 All the above can produce a vritual image 1 Plane mirror 2 Concave mirror 3 Convex mirror 4 Cylindrical mirror The focal length of a concave mirror is f and the distance from the object to the principle focus is x 1
Physics
Geometrical Optics
6 The refractive index of the material of a prism is 2 and the angle of the prism is 30 One of the two refracting surfaces of the prism is made a mirror inwards by silver coating A beam of monochromatic light entering the prism from the other face will retrace its path after reflection from the silvered surface if its angle of incidence on the prism is 1 60 2 Zero 2 45 A
Physics
Geometrical Optics
1 A 2C 2 A 2C 3 A A ray of monochromatic light is incident on one refracting face of a prism of angle 75 It passes through the prism and is incident on the other face at the critical angle If the refractive index of the material of the prism is 2 the angle of incidence on the first face of the prism is 1 30 2 450 3 60 4 0 prism of small angle A and emerges normally from the opposit
Physics
Geometrical Optics
1 300 2 45 3 A ray of light is incident at angle i on a surface of a prism of small angle A and emerges normally from the opposite surface If the refractive index of the material of the prism is u the angle of incidence i is nearly equal to 3 A 1 A 2 A 2 4 A 2 A prism having an apex angle of 4 and refractive index of 1 50 is located in front of a vertical plane mirror as shown 11 deviated is
Physics
Geometrical Optics
4 90 cm 2 180 cm 3 45 cm 4 360 cm A thick plane mirror shows a number of images of the filament of an electric bulb Of these the brightest image is the 1 First 2 Second 3 Last 4 Fourth Two vertical plane mirrors are inclined at an angle of 60 with each other A ray of light travelling horizontally is dent devietion is
Physics
Geometrical Optics
An incident ray strikes a medium whose relative refractive index with respect to surrounding is 3 at grazing angle 30 If the refraction and reflection both take place at the boundary The angle between reflected and refracted rays is 1 40 3 50 2 60 4 90
Physics
Geometrical Optics
144 A astronomical telescope has objective and eyepiece of focal lengths 40 cm and 4 cm respectively To view an object 200 cm away from the objective the lenses must be separated by a distance 2016 me ito a a c 37 3 cm 50 0 cm b 46 0 cm d 54 0 cm
Physics
Geometrical Optics
In the figure shown there is a coin placed at the bottom of the bucket that contains two immiscible liquids transparent the apparent depth of the coin from surface as seen normally from the above is 1 3d 3 5d 2 2d 2 d 2 4 3d 2 5d
Physics
Geometrical Optics
43 The angle of incidence for a ray of light at a refracting surface of a prism is 45 The angle of prism is 60 If the ray suffers minimum deviation through the prism the angle of minimum deviation and refractive index of the material of the prism respectively are 2016 a 45 1 2 b 30 2 b 15 1
Physics
Geometrical Optics
11 A thin prism P of refracting angle 3 and refractive index 1 5 is combined with another thin prism Q of refractive index 1 6 to produce dispersion without deviation Then the angle of prism Qis 1 3 3 3 5 2 2 5 4 4
Physics
Geometrical Optics
2 In the given figure O is the point object and I represents its real image from a concave mirror of focal length f then symbols have their usual meaning 1 f 3 f x x 2 2x x X X X1 C 2 f x x 4 f x x 2 EN PARK CO NAN
Physics
Geometrical Optics
10 A converging lens of glass has its optica power P in the air If it is medium whose refractive index immersed in is less tha EEN A that of lens then its optical power will be 1 More than P 2 Less than P 3 P 4 Cannot be calculated
Physics
Geometrical Optics
141 A beam of light consisting of red green and blue colours is incident on a right angled prism The refractive index of the material of the prism for the above red green and blue wavelengths are 1 39 1 44 and 1 47 respectively 2015 RSP pait Blue Green Red 45 1
Physics
Geometrical Optics
A ray of light passes through an equilateral prism in such a manner that angle o incidence is equal to angle of emergence and each of those angles is equal to of angle of prism The angle of deviation is O 30 O 37 42 45
Physics
Geometrical Optics
he dispersive power of material of a lens is 0 04 and mean focal length of lens s 15 cm The difference in focal lengths of lens for violet and red colour is 03 mm 04 mm O 5 mm 6 mm
Physics
Geometrical Optics
If an object is 8 cm from a lens and produces an image 4 cm from the lens what is the magnification factor M same size of the object triple size of the object double size of the object half the size of the object