Geometrical Optics Questions and Answers

represents the refractive index when a light ray goes medium i to medium j then the product 21 X 32 X 43 is equal to a l 32 1 If from b H 42 d 1 14

6 converging lens of focal length 20 cm The 62 emergent light falls or a screen placed 30 cm beyond the lens An opaque plate with a triangular aperture side 1 cm is in contact with the lens f 20 cm Triangular aperture Opaque plate K 30 cm k Which one of the following diagrams best shows to appearance of the patch of light seen on the screen 1 5 cm Screen 3 xxx 100 2 Aperture side 1 0 cm 4 1 0 cm

50 A ray falls on a prism ABC AB BC and travels as ulb shown in figure The minimum refractive index of the prism material should be 1 2 2 3 2 2 3 1 5 A B 90 90 4 3

31 Three prisms of crown glass each have angle of prism 9 and two prisms of flint glass are used to make direct vision spectroscope What will be the angle of flint glass prisms if u for flint is 1 60 and u for crown glass is 1 53 a 11 9 c 15 3 b 16 0 d 9 11

V A cylindrical laser beam of diameter 4mm and power 10mW is incident on a convex lens of focal length 10 cm kept 2m away Intensity at image will be 1 0 29 MW m 3 10 MW m TEX 2 7 MW m 4 29 MW m

D Rays of light fall on the plane surface of a half cyl inder at an angle 45 in the plane perpendicular to the axis see figure Refractive index of glass is 2 Discuss the condition that the rays do not suffer total internal reflection

35 What is the position and nature of image formed by lens combination shown in figure where fi and f are focal lengths 2 JEE Main 2019 12 Jan Shift l 2 cm O K 20 cm A B f 5 cm 5 cm 20 a cm from point B at right real I 3 b 70 cm from point B at right real c 40 cm from point B at right real d 70 cm from point B at left virtual

9 Angle of prism is A and its one surface is silvered Light rays falling at an angle of incidence 2A on first surface return back through the same path after suffering reflection at second silvered surface Refractive index of the material of prism is 1 2 sin A 2 2 cos A 3 12 1 2 cosA 4 tanA

12 What should be the value of refractive index n of a glass rod placed in air so that the light entering through the flat surface of the rod does not cross the curved surface of the rod irrespective of the angle of incidence i 1 n 2 3 n 2 air glass 2 n n 4

29 A conversing beam of rays is incident on a diverging lens Having passed though the lens the rays intersect at a point 15 cm from the lens on the opposite side If the lens is removed the point where the rays meets will move 5 cm closer to the lens The focal length of the lens is a 10 cm b 20 cm d 5 cm c 30 cm

59 A light ray is travelling through a ring of an optical fibre which is made of four different glasses shown below but each part has the same geometrical thickness Their respective refractive indices are shown The light ray will take the maximum time in crossing the part 1 I Part I Part IV 1 51 1 52 1 54 1 53 Part II Part III 2 11 in all

In an astronomical telescope in normal adjustment a straight black line of length L is drawn on inside part of objective lens The eyepiece forms a real image of this line The length of this image is The magnification of the telescope is Re AIPMT 2015 1 3 L 1 L 2 1 4 L 1 L I

43 The angle of a glass prism is 4 50 and its refractive index is 1 52 The angle of minimum deviation will be 1 1 5 2 2 3 3 4 5 4 20

Calculate resolving power of microscope having focal length and diameter of objective lens as 5 cm and 1 cm 900 nm 1 1 82 x 10 m 2 5 x 105 m 3 0 9 x 105 m 4 3 x 105 m

his is made of glass of An equic refractive index 1 5 and has a focal length of 10 cm in air The lens is cut into two equal halves along a plane perpendicular to its principal axis to yield two plano convex lenses The two pieces are glued such that the convex surfaces touch each other If this combiantion lens is immersed in water of refractive index 4 3 its focal length in cm is 3 20 4 40 1 5 2 10 85

When the sun is directly overhead a narrow shaft of light enters an ancient temple through a small hole in the ceiling and falls on a mirror placed on the floor to reflect the beam on to the ceiling At what speed will the reflected spot move across the ceiling is xn cm min The separation between ceiling and floor of the temple is 10 m Duration of a day 24 h Find x

An object is placed 20 cm from the surface of a convex mirror and a plane mirror is set so that virtual images formed by two mirrors coincide If plane mirror is at a distance of 12 cm from object then the focal length of convex mirror is 1 5 cm 2 10 cm 3 20 cm 4 40 cm

9 An optical of refractive index n surrounded by a transparent cladding of slightly lower index n If fibre is kept in medium of refractive index no then maximum acceptance angle 0 on the axis of the core is given by e no De 1 sinee 3 sine n n no n n 2 n n cladding n core n cladding 2 sinee 4 sinee axis M 1 no 7 7

ith a a the y of be 8 Check Your The maximum value of index of refraction of a material of a prism which allows the passage of light through it when the refracting angle of the prism is A is 1 1 sin 3 1 tan 2 A 2 2 2 1 cos A 2 4 1 cot A 2

Let the x z plane be the boundary between two transparent media Medium 1 in z20 has refractive index of 2 and medium 2 with z 0 has a refractive index of 3 A ray of light in medium 1 given by the vector A 6 31 8 3j 10k incident on the plane of separation The angle of refraction in AIEEE 2011 medium 2 is a 30 c 60 b 45 d 75

light falls 63 A parallel beam of monochromatic on a combination of a convex lens and a concave lens of focallengths 15 cm and 5 cm If the light emerges parallel from the concave lens the distance between the lenses is 1 20 cm 2 3 cm 3 10 cm 4 45 cm

A point object is placed at a distance of 1000 mm from a concave mirror of focal length 400 mm If the object is moved towards the mirror by 200 mm the image moves by a distance of A 133 3 mm towards mirror C 30 mm towards mirror B 133 3 mm away from the mirror D 30 mm away from the mirror

A plane mirror is placed 22 5 cm in front of a concave mirror An object is placed between the two mirrors at 7 5cm from plane mirror so that the first image in both the mirrors coincides The focal length of mirror a 20 cm b 15 cm c 10 cm d 5 cm

imple A convex mirror used for rear view on an automobile has a radi curvature of 3 00 m If a bus is located at 5 00 m from this min find the position nature and size of the image

lly of equal height h are 4 12rad s Two candles distance of a from each other The distance between each candle and the nearest wall is also a With what speed the shadow of the left side candle will move along the left wall if left side candle burns down in the time t and the right side in the time t at a a 21 1 pak h a a h 2 21 1 1 1 h 12 1

5 A ray of light travelling from air towards glass of refractive index u is incident normally This ray starts rotating at constant angular velocity about the point of incidence The angular velocity of refracted ray is w2 then 1 101 13 0 4 Both 2 and 3 2 1

43 A telescope with objective of focal length 60 cm and eye piece of focal length 5 cm is focused on a far distance object such that the parallel rays emerge from eye piece If object subtends an angle 2 on objective then angular width of the image is 1 62 3 24 2 48 4 12

A ray of light incident on a glass sphere refractive index 3 suffers total internal reflection before emerging out exactly parallel to the incident ray The angle of incidence was a 75 b 30 c 45 d 60

Two identical glass g 3 2 equi convex lenses of focal length f each are kept in contact The space between the two lenses is filled with water w 4 3 The focal length of the combination is W NEET 2016 4f 3f a f 3 b f d 3 4 c

In an experiment for determination of refractive index of glass of a prism by i 8 plot it was found that a ray incident at angle 35 suffers a deviation of 40 and that it emerges at angle 79 In that case which of the following is closest to the maximum possible value of the refractive index JEE Mains 2016 3 1 6 4 1 7

D A biconvex lens has a radius of curvature of magnitude 20 cm Which one of the following options describe best the image formed of an object of height 2 cm placed 30 cm from the lens AIPMT Prelims 2011 1 Real inverted height 1 cm 2 Virtual upright height 1 cm 3 Virtual upright height 0 5 cm 4 Real inverted height 4 cm

32 If R and R are the radii of curvature of the spherical surfaces of a thin lens and R R then this lens can R R 1 Correct myopia 2 Correct hypermetropia 3 Correct presbiopia 4 Correct astigmatism

White light may be considered to be a mixture of waves of ranging between 3900 and 7800 An oil film of thickness 10 000 A is examined normally by the reflected light If u 1 4 then the film appears bright for A 4000 A 4667 5600 7000 C 4000 5091 A 5600 A B 4308 5091 6222 A D 4667 6222 7000 DOC DX 2M Dx 622 2

A ray of light travelling in a transparent medium of refractive index u falls on a surface separating the medium from air at an angle of incidence 45 For which of the following value of u the ra can undergo total internal reflection of 1 1 25 3 1 40 2 1 33 12 1 0 4 1 50

32 The output of gate is low when at least one of its input is high This is true for 1 NOR 2 OR 3 AND 4 NAND 3

A thick mirror forms multiple image Which image is brightest 1 First image 2 Second image 3 Third image A All

3 A prism can produce a minimum deviation 8 in a light beam If three such prisms are combined the minimum deviation that can be produced in this beam is a 0 b 8 c 28 d 38

A short linear object of length L lies on the axis of a spherical mirror of focal length fat a distance u from the mirror Its image has an axial length L equal to 71 2 1 2 4 a L c L f u f u f f b L u f f f d L u f AMU Med 2012 AIIMS 2009

3 White light consists of wavelengths from 400 nm to 700 nm What will be the wavelength range seen when white light is passed through glass of refractive index 1 55 Ang 259 06

transmitted light Find the light For the combination of one prism and 2 lenses shown in figure find the size of the final image in mm when the object length 1 cm is located as shown in the figure Refractive index of material from which prism is made is 1 5 45 1 16cm H 1 5 10cm 45 6cm 5cm f 20cm f 10cm

7 When a biconvex lens of glass having refractive index 1 47 is dipped in a liquid it acts as a plane sheet of glass This implies that the liquid must have refractive index 1 greater than that of glass 2 less than that of glass 3 equal to that of glass 4 less than one

An object is placed in front of two convex lenses one by one at a distance u from the lens The focal lengths of the lenses are 30 cm and 15 cm respectively If the size of image formed in the two cases is same then u is 1 15 cm 2 20 cm 3 25 cm 4 30 cm

13 How far should an object be from a concave spherical c inversely proportional to x image one ninth its size by about 14 As the position of an object in front of a concave spherical mirror of 0 25 m focal leng A point object is placed at a dis varied the position of the image varies Plot the image distance as a function of the from a concave mirror If the o distance letting the later change from 0 to Where is the image real Where virtual Light from a 0 4 cm away from the mir b 0 4 cm towards the mirro focal length 21 cm of the concave

A parallel beam of light in incident on a liquid surface such that the wave front makes an angle 30 with the surface and has a width of 3 m the width of the refracted beam is at4 3 1 3 m 2 3m 3 11 3 m 4 11 3 m

32 A person who can see distinctly from a distance of 1 5 m wants to read a book placed at a distance of 25 cm Power of the required lens is

41 Focal length of objective eye piece and inverting lens of a terrestrial telescope are 20 cm 10 cm and 5 cm respectively Length of the tube containing these lenses at normal adjustment is 1 30 cm 2 35 cm 3 50 cm 4 40 cm

4 1 6 133 The focal length of a biconvex lens is 20 cm Duand its refractive index is 1 5 If the radii of ubt curvatures of two surfaces of lens are in the ratio 1 2 then the larger radius of curvature is in cm 1 10 2 15 3 20 4 30

15 In a vertically placed container filled with water a small light source is at bottom What would be the speed in m s of the image of the light source with respect to an stationary observer watching normally if the water level falls with constant speed of 4 m s

1 3 given ray as condition of total internal reflection of this ray the required refractive index of prism will be 3 1 2 13 45 incident ray 2 4 2 1 2 7 c Sini Sin C Sinusz 1 M X Va M

In a compound microscope focal length of objective and eyepiece lens is 4 cm and 8cm respectively If length of tube is 30 cm then magnifying power for normal adjustment will be 1 20 3 42 2 14 06 3 23 43 4 15 3