# Geometrical Optics Questions and Answers

Physics
Geometrical Optics
What is the nature of the image obtained from surface of the spoor bulged outward and to what type mirror we can approximate it to A Inverted and concave mirror B Inverted and convex mirror C Erect and convex mirror Frect and e mirror
Physics
Geometrical Optics
An object of 5 cm in size is placed at a distance of 20 cm from concave mirror of focal length 15 cm what is the nature of the image A Real inverted enlarged B Real erect diminished C Virtual inverted diminished D Virtual erect diminished
Physics
Geometrical Optics
A student traces the path of a ray of light through a rectangular glass slab for the different values of angle of incidence He observes all possible precautions at each step of the experiment At the end of the experiment on analysing the measurements which of the following conclusions is he likely to draw A Zi Ze Zr B Zi Ze r C Zi Ze Zr D ZiZe r
Physics
Geometrical Optics
A man s face is at a distance p 15 cm in front of a concave spherical shaving mirror If the image is erect upright and 1 5 times largen than the object what is the radius of curvature of the mirror
Physics
Geometrical Optics
24 In single slit diffraction experiment first minima of red light A1 660 nm coincides with first maxima of other wavelength 2 What is the value of 1 440 nm 2 470 nm 3 550 nm 4 690 nm Find the ratio of least soparation betwe 5
Physics
Geometrical Optics
In Young s double slit experiment the intensity at a point where the path difference is being the wavelength of the light used is I If lo denotes the maximum intensity then is equal to O 1 2 O 3 2 O 1 2 O 3 4
Physics
Geometrical Optics
experiment the slit separation d is 0 3 mm and the screen distance D is 1 m A parallel beam of light of wavelength 600 nm is incident on the slits at angle a as shown in figure On the screen the point O is equidistant from the slits and distance PO Which of the following statements s is are correct is 11 0 mm 0 36 D A For TC B Fringe spacing depends on 0 36 C For a Screen y P degree there will be destructive interference at point O TC D For a 0 there will be constructive interference at point P 0 degree there will be destructive interference at point P 201
Physics
Geometrical Optics
Fill in the table below each column of which refers to a spherical mirror and real object Distances are in centimeters if a number has no plus or minus sign in front of it find the correct sign C Type f cm P cm Real Image Upright A Concave 40 50 B 20 0 5 20 30
Physics
Geometrical Optics
Focal length of an equiconvex lens is 20 cm The refractive index of material of the lens is 1 5 Now one of the curved surface is silvered At what distance from the lens an object is to be placed so that image coincides with the object
Physics
Geometrical Optics
A convex mirror forms the image of an object such that the distance between the object and image is 60 cm and the magnification produced is 1 4 The focal length of the mirror will be Question Type Single Correct Type 1 8 6 cm 2 6 2 cm 3 10 cm 4 16 cm
Physics
Geometrical Optics
1 m Water n 1 33 1 m An observer is looking through a 1 meter thick clear water tank If an object is located at 1 m from the tank on the other side of the observer calculate the virtual location of the object seen by the observer
Physics
Geometrical Optics
Two identical glass g 3 2 equiconvex lenses of focal length f are kept in contact The space between the two lenses is filled with water w 4 3 The focal length of the combination is Question Type Single Correct Type 1 f 2 f 2 3 4f 3
Physics
Geometrical Optics
44 Calculate the radius of the image of the moon formed by the objective of an astronomical telescope having focal length 10 m Given the diameter of the moon 3 48 103 km and its distance from the earth 3 84 x 105 km Ans 4 53 x 10 2 m 45 Two convex lenses of focal lengths 0 20 m and 0 01 m are provided to you How shall you arrange
Physics
Geometrical Optics
5 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 3 30 2 45 4 zero
Physics
Geometrical Optics
In the figure given below a hemisphere made of glass u 1 5 is shown Find the location of final image for the object O placed at a distance 40 cm from point P on the hemisphere Consider outside medium as air P 040 cm Hemisphere radius 40 cm 1 5
Physics
Geometrical Optics
10 A far sighted person can see object beyond 71 cm clearly if separation between glasses and eye 3 lens is 2 cm then find focal length of glass 1 23 cm 2 34 5 cm 3 18 4 cm 4 30 cm
Physics
Geometrical Optics
The formula R radius of curvature R approaches infinity Hence becomes zero Substituting this in above R we get formula for the plane surfacesh 0 The distances u and y are measured from the plane of interface png V u a Water and glass together act as diverging lens b Water and glass together act as converging lens vu CLASSROOM PACKAGES CLARITY ACHIEVER IV A lemon kept in water in a glass tumbler appears to be bigger than its actual size when viewed in sides because I c Water acts as converging medium where as glass will act as diverging medium H Water acts as diverging medium where as glass will act as converging medium a Both A and c A is true B Assertion A Reason R object is pre a both A an b both A a c A is true When a parallel beam of light rays passes through an air bubble in water then it will become dive eam because The ray of a Real For a fish a farther c movin
Physics
Geometrical Optics
Example 30 1 Two plane mirrors M and M are inclined at angle 0 as shown A ray of light 1 which is parallel to M strikes M and after two reflections the ray 2 becomes parallel to M Find the angle 0 2 M N 0 A Fig 30 23 Solution Different angles are as shown in Fig 30 24 In triangle ABC B 0 a an ala eee 1 777 M a 90 0 A 60 C Fig 30 24 0 0 0 180
Physics
Geometrical Optics
An object is placed 21 cm infront of a concave mirror of radius of curvature 20 cm A glass slab of thickness 3 cm and refractive index 1 5 is placed closed to the mirror in space between the object and the mirror Find the position of final image formed if distance of nearer surface of the slab from the mirror is 10 cm 3cm 0 10 cm 21cm
Physics
Geometrical Optics
An observer looks at a distant tree of height 10 m with a telescope of magnifying power of 20 To the observer the tree appears JEE Mains 2016 1 20 times nearer 3 10 times nearer 2 10 times taller 4 20 times taller int for determination of refractive index of glass of a prism by i 8 plot it was found d that it emerges at angle 79 In that case
Physics
Geometrical Optics
10 The angular magnification of telescope is 30 If all the light which passes through objective lens of diameter 80 cm also passes through eye piece lens then find out diameter of eye piece lens 1 cm cm 3 2 8 cm 3 013 8 cm 4 0 cm
Physics
Geometrical Optics
3 A microscope is focussed on a mark on of paper and then a slab of glass of thickness cm and refractive index 1 5 is placed over the mark How should the microscope be moved to get the y mark in focus again nward
Physics
Geometrical Optics
Focal length of converging combination of two ler is 20 cm The ratio of dispersive power is 2 One of the focal length will be 1 6 cm 2 10 cm 3 15 cm 4 20 cm
Physics
Geometrical Optics
60 7 As shown in figure light P enters to slab at an angle 60 with normal and inside slab Q makes total internal reflection Find minimum refractive index of slab 1 1 72 3 1 32 2 1 52 4 1 12
Physics
Geometrical Optics
A small coin is resting of filled with a liquid A ray of light from the coin travels upto the surface of the liquid and moves along its surface see figure 22 4 cm 3 cm a g g pia R Maz Coin How fast is the light travelling in the liquid 1 1 2 x 108 m s 2 1 8 x 108 m s 3 2 4 x 108 m s 4 3 0 x 108 m s wh PS 11 N
Physics
Geometrical Optics
If there is a very small air bubble inside a glass sphere u 1 5 of radius 10 cm at distance 4 cm below its surface then its apparent depth when viewed normally from outside will be approximately Only one correct answer A 2 cm B 2 4 cm C 3 1 cm D 3 6 cm
Physics
Geometrical Optics
Q12 Light is incident on a right angle prism as shown in figure On the hypotenuse of prism a drop of liquid is placed The refractive index of prism is 1 62 The maximum refractive index that the liquid may have if the light is to be totally reflected is 60 90 O A 1 52 O B 1 38 O C 1 40 O D 1 62 Liquid drop 30
Physics
Geometrical Optics
A convex lens is made of material having refractive index 1 25 Both the surfaces are convex It if is dipped in a liquid transparent of refractive increase 1 4 it will behaves like A convergent lens O A sheet O A divergent lens A prism
Physics
Geometrical Optics
PHYSICS Which of the following statements is are correct about the refraction of light from a plane surface when light ray is incident from denser medium C is critical angle T A The maximum angle of deviation during refraction is 2 C it will be at an angle of incidence C PHYSICS B The maximum angle of deviation for all angles of incidence is 2C when angle of incidence is slightly greater than C C If angle of incidence is less than C then deviation increases with increase in angle of incidence D If angle of incidence is greater than C then angle of deviation decreases if angle of incidence is increased
Physics
Geometrical Optics
A point object is placed at 30 cm from a convex glass lens n 2 of focal length 20 cm The fina image of object will be formed at infinity if A another concave lens of focal length 60 cm is placed in contact with the convex lens B another convex lens of focal length 60 cm is placed at 30 cm from the first lens 4 C the convex lens is immersed in a liquid of refractive index O 3 9 D The convex lens is immersed in a liquid of refractive index 8
Physics
Geometrical Optics
Question No 1 A double slit interference experiment is carried out in air and the entire arrangement is dipped in water as a result the ratio of path differences for fifth minima is A B 413 X 1
Physics
Geometrical Optics
A screen is placed 90 cm away from an object An image of the object is formed on the screen by the same convex lens placed at two different locations separated by 30 cm The focal length of the lens is A 15 cm B 20 cm C 25 cm
Physics
Geometrical Optics
Doesn t a glass slab just shifts the image laterally Then h ow will the distance change Please clear my specific dou bt Plane glass slab is kept between a model and a plane mirror The mirror is 50 cm away from the model The glass slab has a thickness of 15 cm and refractive index of 1 5 At what distance in cm from herself will the model see her image 40 50 80
Physics
Geometrical Optics
Q6 Assertion The emergent ray is parallel to the direction of the incident ray Reason The extent of bending of the ray of light at the opposite parallel faces air glass interface and glass air interface of the rectangular glass slab is equal and opposite
Physics
Geometrical Optics
ALLEN 35 Shown in the figure is a bi convex lens made 35 of different transparent strips of two different refractive indexes If the parallel rays of light is incident on the lens then select INCORRECT statement n n 1 rays will intersect before focussing 2 rays will be focussed at two different points 3 the lens may have four focal points different from each other 4 None of the these f t 2
Physics
Geometrical Optics
Statement A For a virtual object convex lens forms real erect and diminished image Statement B For a virtual object concave lens always forms virtual image Assume lens material is denser than surrounding medium in both cases 1 Both statement A and B are true 2 Statement A is true Statement B is false 3 Statement A is false Statement B is true 4 Both statement A and B are false
Physics
Geometrical Optics
Let the index of refraction for air be 1 00 and the index of refraction for the type of glass in this problem be 1 56 A light beam in air has an angle of incidence of 62 at the surface of a glass plate a Calculate the angle of reflection in degrees b Calculate the angle of refraction in degrees
Physics
Geometrical Optics
A convex lens is made of two different materials having radius of curvature of surface A and surface B as 25 cm and 24 cm respectively The effective focal length of lens is A B H 1 5 O 75 cm 4 75 cm 50 cm O 30 cm Reload H 1 8
Physics
Geometrical Optics
Consider the following statements regarding the real images formed with a converging lens Real images can be seen only if the image is projected onto the screen The real image can be seen only from the same side of the lens as that on which the object is positioned I II III Real images produced by converging lenses are not only laterally but also longitudinally inverted as with mirrors Which of the above statement statements is are incorrect A Only I and III B All three C None D Only II
Physics
Geometrical Optics
A convergent lens of 6 diopters is combin with a diverging lens of 2 diopters Find power of combination 1 4 diopter 2 6 diopter 3 8 diopter 4 10 diopter
Physics
Geometrical Optics
Optical fibre consists of core and claddin whose refractive index are related as 1 core clading 2 core clading 3 core clading 4 No relation between them
Physics
Geometrical Optics
If an object is placed in front of a conca mirror and the lower half of the mirror covered with opaque material then w happens 1 lower half of the object will be seen as im 2 upper half of the object will be seen as im 3 No change in the image will taken pl 4 image will be completely formed with less inte
Physics
Geometrical Optics
Unpolished half is unpolished Flashlight beam O In a dark room this coin is placed face up on the floor and illuminated with a thin beamed flashlight as shown in figure A and B look at the coin from the position as indicated in figure Beye A Polished coin A eye Floor According to A which half of the coin if either is brighter 1 The polished half 2 The unpolished half 3 Both halves look equally bright
Physics
Geometrical Optics
A passenger in an aeroplane shall 1 Never see a rainbow 2 may see a primary and a secondary rainbow as concentric circles 3 may see a primary and a secondary rainbow as concentric arcs 4 shall never see a secondary rainbow
Physics
Geometrical Optics
A double convex lens with both faces of the same radius of curvature is manufactured from a glass of refractive index 1 54 If the radius of curvature is 27 cm the focal length of the lens is A 50 cm B 25 cm C 18 cm D 9 cm
Physics
Geometrical Optics
A prism is made up of flint glass whose 30 dispersive power is 0 053 Find the angle of dispersion if the mean refractive index of flint glass is 1 68 and the refracting angle of prism is 3 1 20 08 3 0 208 2 10 08 4 0 108 ft A 3
Physics
Geometrical Optics
A diminished image of an object is to be 34 obtained on a screen 1 0 m away from it This can be achieved by approximately placing 1 a convex mirror of suitable focal length 2 a concave mirror of suitable focal length 3 a convex lens of focal length less than 0 5 m 4 a concave lens of suitable focal length
Physics
Geometrical Optics
9 10 What is the focal length of a convex lens of focal length 30 cm in contact with a concave lens of focal length 20 cm Is the system a converging or a diverging lens Ignore thickness of the lenses 11 A compound microscope consists of an objective lens of focal length 2 0 cm and an eyepiece of focal length 6 25 cm separated by a distance of 15 cm How far from the objective should an object be
Physics
Geometrical Optics
Candle C Lens L Screen S 1 the screen in the direction of the lens or the lens in the direction of the screen 2 the screen in the direction of the lens or the lens away from the screen 3 the screen away from the lens or the lens in the direction of the screen 1 neither the screen nor the lens
Physics
Geometrical Optics
Q No 19 An object is placed at 20 cm from a convex mirror of focal length 10 cm The image formed by the mirror is 1 2 3 Correct Answer 3 Your Answer 4 Status incorrect Real and at 10 cm from the mirror Virtual and at 10 cm from the mirror Virtual and at 20 3 cm from the mirror Real and at 20 3 cm from the mirror Add to Bookmark List 22 Two massos each of mass Mare attached to the end of a rigid massless rod Right Answer 21 Your Answer 2 Difficulty Lovel low I Topic physics rotational motion Poor Stat Unattemptod 27 8 Correct 63 0 Incorrect 9 2 A rupoc coin starting from rost rolls down a distance of 1 m on a plane in Dienst A