Geometrical Optics Questions and Answers

The separation between point object P and the thin convex lens is 40 cm initially at a time t 0 At t 0 the object and lens starts motion with constant velocities 2 cm and 4 cm s respectively towards right Then the speed of image formed by the lens a a time t 10 s is P 2cm s 40 cm f 20 cm 4cm s

thickness t 1m at the origin The refractive index of of the transparent slab varies as 1 e Them choose the correct option s SR IIT CO SC Narayana IIT Academy disha ww 1800 419 1828 A dull mind gets bored easily A curious mind expands forever Ifm Jay SRA of the Page No 5 04 07 21 OSR IIT CO SC JEE Adv GTA 16 P II Q P 1 A The equation of the trajectory of light in the slab is x 1 e B The equation of the trajectory of light in the slab is x 1 e C The coordinates 1 the point P at which the light emerges from the slab are D The coordinates of the point P at which the light emerges from the slab are e 1

Ray Optics and Optical Instruments 109 The refractive index of a prism is 2 If the angle of prism is 60 at what angle a ray must be incident on it so that it suffers minimum deviation 1 30 2 45

In an experiment to find focal length of a convex lens by displacement method magnification obtained are 2 and respectively for two positions of lens separated by distance d 30 cm Focal length of lens is 2 14 A 10 cm B 20 cm C 30 cm D 40 cm 15 Distance between two pins to locate positions of object and image is A 60 cm B 90 cm C 120 cm 16 object pin and lens when magnification m 2 is obtained is B 20 cm C 30 cm D 40 cm Distance between A 10 cm D 150 cm

3 55 cm 4 45 cm 9 In displacement method there are two positions of a lens for which two distinct images are formed on a screen First position of the lens is at a distance of x from the object and second is at a distance 2x the focal length of the lens is 001 1 3 object x 3 2x 3 H X 1 2x 2 2x 4 6x

0 A bulb is placed at a depth of 2 7 m inside water and a floating opaque disc is placed over the bulb so that the bulb is not visible from the surface The minimum diameter of the disc is Refractive index of water is 4 3 1 6m 3 12m 2 9m 4 14m

97 In a tank a 4 cm thick layer of water 3 floats on a 6 cm thick layer of an organic liquid u 1 50 Viewing at normal incidence how far below the water surface does the bottom of tank appear to be 1 4 cm 3 6 cm 2 5 cm 4 7 cm

0 A lens having focal length f and aperture of diameter d forms an image of intensity I in central region of d Aperture of diameter c f and lens is covered by a black paper Focal length of lens and intensity of image now will be respectively CBSE AIPMT 2010 a f and and 1 4 3 4 2 b 3f 4 d and 2 2 2

107 A system of two concavo convex glass system as shown in the figure of radius of curvature 50 cm 1 25 cm 3 Zero rar 3 2 each and respective refractive indices and The focal length of the system is 3 2 100 cm 4 Infinite 13 4

105 When a lens of power PO and refractive index u is kept in a medium of refractive index 0 its power will be 106 1 PO PH 3 1 Ho 2 4 P Ho P H 1 H person having poor point 10 murer reading

5 ABC is a right angled prism of transparent material of refractive index such that ZB is smaller than ZA as shown in figure A ray of light incident normally on the face AB emerges parallel to the incident ray after two internal reflections then theeet minimum value of is 1 3 1 sin A sin A sin R C 2 sinB B Telegram oeet 4 sin A sin B

91 A far sighted person has his near point 50 cm Find the power of lens he should use to see at 25 cm clearly 1 1D 2 2D 3 2D 4 1D 2 A microscope has an objective of 5 mm focal 9

4 In the figure shown For an angle of incidence 45 C at the top surface what is the minimum refractive index needed so that no light will emerge from vertical face AD 1 3 2 1 2 paper D 13 2 2 C 4 2

106 A person having near point 40 cm uses a reading lens of focal length 10 cm The maximum magnification he can obtain is 1 4 3 3 5 2 5 4 Infinity ram neet

3 2 4 2 5 85 A convex lens of focal length f and dispersive power is combined with a concave lens of focal length f2 and dispersive power 2 is such a way that an achromatic doublet of focal length 40 cm is obtained If respectively 1 3 40 3 40 3 per 20 20 00 02 2 3 1 then f and f2 in cm are 2 20 4 20 40 we we

To get four images of an object placed symmetrically between two plane mirrors the angle between the mirrors must be 1 90 3 72 2 36 4 120

88 A ray is incident on face PQ at an angle of 45 The refracted ray undergoes reflection on face PR and retraces it s path The refractive index of the prism is 1 2 3 1 5 30 R 3 2 2 4 1 33

4 both 1 and 2 are possible 3 A convex lens made of a material of refractioneetque index 1 5 and having a focal length of 10 immersed in a liquid of refractive index 3 0 will behave as a 1 Converging lens of focal length 10 cm 2 Diverging lens of focal length 10 cm 10 3 Converging lens of focal length cm 4 Diverging lens of focal length 30 cm lens 48

A glass clad fiber is made with the core glass of refractive index 1 6 and the cladding is doped to give a fractional index difference of 0 006 Calculate 1 the refractive index of the cladding ii the critical angle iii the numerical aperture and iv the acceptance angle Select the nearest answer in the options given by doing calculation up to the third decimal a i 1 590 ii 83 72 iii 0 176 and iv 10 14 b i 1 490 ii 93 72 iii 0 276 and iv 20 14 c i 1 690 ii 73 72 iii 0 176 and iv 15 14 d i 1 590 ii 83 72 iii 0 276 and iv 20 14

Q2 NTA Test 02 Numerical A point object is moving with a speed v in front of an arrangement of two mirrors as shown in figure If the velocity y of image in mirror M wit respect to image in mirror M is n v sin find n mathong mathong matho M mathongo 14 hongo mathonge m mathongo mathongo mathonga mathongo 4 07 pm

The focal lengths of the lenses of an astronomical telescope are 50 cm and 5 cm If the image is formed at the least distance of clear vision then the length of the telescope is 275 1 cm 6 3 55 cm 325 6 4 45 cm 2 cm

5 Two plane mirror are inclined at angle 0 as shown in figure If a ray parallel to OB strikes the other mirror at P and finally emerges parallel to OA after two reflections then 0 is equal to A 44 www 0 TB

54 In a vessel two insoluble liquids are filled as shown in the figure The effective refractive index of the combination for normal view is 1 1 33 3 1 45 2 1 26 4 1 58 10 cm 10 cm 6 60 The cm lenc 1 3 61 An has leng obje 3

An object is placed at a distance x from the focus of a concave mirror of focal length f Find the distance of image formed from the focus 1 2 2 3 fx 2 4 4 fx

1 An equiconvex lens is prepared from glass 1 5 having radius of curvature 25 cm One of the surface is silvered from outside Where should an object be placed before this lens so that image is formed on the object itself 1 12 5 cm 3 100 cm 2 25 cm 4 125 cm

ging lens 1 Bcal lengin 4 In a spherical paper weight R 10 cm made of glass of refractive index 1 5 and object is embedded at a distance 5 cm from its centre What is the apparent position of the object when seen from the opposite side R D C 5 cm 1 10 cm behind centre 2 10 cm behind P 3 15 cm behind centre 4 5 cm behind P 2

25 A presbyopic old patient has near point 30cm The optical power for the corrective lens for seeing object placed at normal near point 25cm is 2 76 IN NI ED 3 compound microscopo UGOD On biootivo long

Aakash Institute 22 A luminous object and a screen are fixed distance D apart A converging lens of focal length capable of forming a real image of the object on the screen will do so for two positions of the lens that are separated by distance d such that 1 d D D 4f 3 d D D 4f 2 d D D f 4 d D 2D f 27 In a eye tele of a Fina 1 3 28 An

23 A liquid of Refractive index 1 6 is contained in the cavity thin of a glass specimen of refractive index 1 5 as shown in the figure If each of the curved surface has radius of curvature of 0 20 m then the arrangement behaves as a Glass Liquid 1 Converging lens of focal length 0 25 m 2 Diverging lens of focal length 0 23m 3 Diverging lens of focal length 0 17m 4 Converging lens of focal length 0 72m

Unpolarised light is incident from air on a plane surface of a material of refractive index u At a particular angle of incidence i it is found that the reflected and refracted rays are perpendicular to each other Which of the following options is correct for this situation NEET 2018 1 Reflected light is polarised with its electric vector parallel to the plane of incidence 2 Reflected light is polarised with its electric vector perpendicular to the plane of incidence 3 tan

1 A person is unable to see an object beyond 30cm Find the power of lens in dioptre to correct the vision 10 2 1 3 3 4 2 In a compound microscope the focal length of objective lens is 1 2cm and focal length of eyepiece is 3 0cm When the object is kept at 1 25cm in front of objective the final image is formed at infinity Magnifying power of compound microscope should be nearest to Use D 25cm 1 200 2 100 4 150 w dw o Chapter Ray Optics and Optical Instruments 1 25cm 3 68cm 2 35cm 4 100cm An object O is kept in air in front of a thin plano convex lens of radius of curvature 10cm It s refractive index is and medium towards right of 20 5 10 3 3 400 3 An astronomical telescope consists of two convex lenses If focal length of objective is 1 0m and angular magnification is 10 find the length of the tube between objective and eyepiece such that final image is formed at infinity 1 1 2m 20 3 2 1 1m 3 1 4m 4 1 5m 4 An object is placed at a distance of 15cm from a 8 convex lens of focal length 10cm Find the distance at which a convex mirror of focal length 10cm should be placed on the other side from the lens so that final image coincide with the object itself 1 20cm 2 10cm 3 15cm 4 30cm 20cm 1 60cm to the left of lens 2 12cm to the left of lens 3 60cm to the right of lens 7 Focal length of plano convex glass lens of refractive index 1 5 is 15cm A small object is placed at A as shown The plane surface is silvered The image will be formed at 9 4 30cm to the left of lens 6 A lens made of glass of refractive index 1 5 has focal length 25cm in air It s focal length in water of 4 refractive index will be plane surface is water of refractive index3 What should be the distance x of the object so that the rays become parallel finally Telegram netquestion paper 1 5cm 3 20cm Ratio of dispersive power of lens combination of lenses is 1 2 10cm 4 None of these 00 1 At 20cm from P 3 At 25cm from P 3 A point object O is placed at distance of 15cm from concave morror between a concave and a plane mirror separated by 25cm Considering 1st reflection from concave mirror position of image after 3rd reflection will be Radius of curvature of concave mirror is 20cm 15cm 10cm for achromatic 2 At 30cm from P 4 At 40cm from P

For an object placed 16 cm in front of a spheric mirror a four times magnified inverted image formed The focal length of the mirror is 1 12 8 cm 2 6 4 cm 3 51 2 cm 4 25 6 cm

2 Two coherent monochromatic point sources S and S of wavelength 600 nm are placed symmetrically on either side of the centre of the circle as shown The sources are separated by a distance d 1 8 mm This arrangement produces interference fringes visible as alternate bright and dark spots on the circumference of the circle Total and Pis number of fringes produced between P close to S P A0 S P 2

Ray Optics and Optical Instruments 10 Find the deviation caused by a prism having 3 refracting angle 4 and refractive index 2 3 3 2 11 From the graph of angle of deviation versus angle

A person is unable to see an object beyond 30cm Find the power of lens in dioptre to correct the vision 1 3 10 3 20 3 2 4 10 3 20 3 7

3 15cm 4 30cm Focal length of plano convex glass lens of refractive index 1 5 is 15cm A small object is placed at A as shown The plane surface is silvered The image will be formed at 20cm 1 60cm to the left of lens 2 12cm to the left of lens 3 60cm to the right of lens 743 2000

4 2 radian Q 19 When a clock is viewed in a mirror the needles exhibit a time which appears to be 8 20 Then the actual time will be 2 3 40 4 3 20 0 20 1 4 40 3 8 20

0 Assertion When monochromatic light is incident on a surface separating two media the reflecte and refracted light both have the same frequency as the frequency of incident light Reason The frequency of monochromatic light depends on media 1 Both assertion and reason are true 3 Both assertion and reason are false 2 Assertion is true but reason is false 4 Assertion is false but reason is true

There are two plane mirror inclined at 40 as shown in the figure A ray of light is incident on mirror M then what should be the value of angle of incidence i so that the light ray retraces its path after striking the mirror M M O 70 O 40 O 50 60 40 M Marks 4 1

59 Two mirrors labelled L for left mirror and L for right mirror in the figure are parallel to each other and 3 0 m apart A person standing 1 0 m from the right mirror L looks into this mirror and sees a series of images The second nearest image seen in the right mirror is situated at a distance 1 2 0 m from the person 3 6 0 m from the person W 2m 1m 2 4 0 m from the person 4 8 0 m from the person

A point object is placed at a point P infront of a plane mirror MN then the position coordinate of the image will be Y N 4 3 II M 4 2 P 2 0 6 0 O 2 3 O 2 0 O 4 0 X Marks

Which of the following statements is correct A A plane mirror can produce a magnified image B Displacement method experiment can be performed with a diverging lens Octwo mirrors inclined at some angle will form infinite number of images of any object placed between them OD Lenses with higher curvature of the refracting surfaces have higher converging or diverging power depending on the nature of th

A light wave is incident normally on a glass slab of refractive index 1 5 If 4 of light gets reflected and the amplitude of the electric field of the incident light is 30 V m then the amplitude of the electric field for the wave propogating in the glass medium will be 1 30 V m 3 24 V m 10 V m 2 4 6 V m

How much water should be filled in a container 21 cm in height so that it appears half filled when viewed from the top of container Given that Hwater 4 3 8 cm 10 5 cm 12 cm 16 cm

The first few electronic energy states for neutral copper atom Z 29 are given as E E E where E being the ground electronic state The states E and E are doubly degenerate due to spin splitting Write the electron configuration of the states and arrange the spectral terms of the split levels following Hund s rules Explain why E E

1 A compound microscope uses an objective lens of focal length 4cm and eyepiece lens 10cm A object is placed at 6cm from the objective lens Calculate the magnifying power of the compound microscope and length of the microscope OOC 7 1 914cm 7 19 14cm 5 14 19cm

Two plane mirrors M and M are placed with their reflecting surfaces making an angle a B A point objec O is placed in between the region of two mirror as shown List I contains information about the image formed and List Il contains corresponding numerical values List I M 1 Total number of images formed by plane mirror M 11 Total number of images formed by plane mirror M III Total number of distinct images formed by mirrors M plus M Number of images which coincide with each IV other List P 2 Q 3 R 4 S 7

4 A person can see clearly objects only when they lie between 50 cm and 400 cm from his eyes In order to increase the maximum distance of distinct vision to infinity the type and power of the correcting lens the NEET 2016 person has to use will be a convex 2 25 diopter b concave 0 25 diopter c concave 0 2 diopter d convex 0 15 diopter

A particle of mass m in the one dimensional energy well 0 x L co elsewhere V x is in a state whose coordinate wave function is given by x Cx L x where c is the normalizatio constant a Determine the expectation value of the energy in the state p x b Calculate the probability that on measurement of energy the particle will be found in its ground stat

For the angle of minimum deviation of a prism to be equal to its refracting angle the prism must be made of a material whose refractive index fait for 1 is less than 1 3 lies between 2 and 1 1 1 3 231afta a fe fu dich 2 is greater than 2 4 lies between 2 and 2 2 23 4 2 3 2 ata