Geometrical Optics Questions and Answers

In an industrial unit physical parameters like temperature pressure and strain are to be monitored continuously Fibre optic sensors are transducers which generally consist of light source coupled with an optical fibre and a light detector held at second end Design a system where these sensors are used to measure the above listed physical parameters explaining principle and working with valid reasons for supporting material to be used 21 50

The magnifying power of a simple microscope when final image is at near point is 3 The focal length of its lens in metres will be least distance of distinct vision is 25 cm 0 05 0 06 0 25

The deviation suffered by a ray is 60 when it is incident on a face of a prism at angle of incidence equal to 30 The angle of emergence is calculated to be equal to 40 The angle of the prism will be 10 20 O 30

Two thin prisms A and B are made of glass of refractive index 1 4 and 1 5 They are combined with each other so that this combination produces dispersion without deviation If refracting angle of prism A is 5 then the refracting angle of second prism will be 5 3 sec 2

A prism has two acute angles of 30 each and refractive index of 1 5 If two parallel light rays AB and CD are incident as shown in the figure the angle between the emergent rays is Use sin 0 75 48 6 B30 CD sec 307

produces a real image of an object located outside the medium irrespective of its location A always may be if refractive index of surrounding medium is greater than 1 may be if refractive index of surrounding medium is less than B V C D Solution N 1 5 1 2 Surface concave to denser medium i e rays go from denser to rarer medium O Text Explanation We have fl fy U none of the above fl fly R 1 Alternative solution fl 11 ff R U V Here using sign convention u 5 R 15

For much larger magnifications one uses two lenses one compounding the effect of the other instead of a single lens as in case of simple microscope because A simple microscope has a limited maximum magnification 9 for realistic focal lengths A simple microscope is very fragile Simple microscopes are very expensive comparison of compound O in microscopes

A concave mirror of centre of curvature R and a rod AB of length are arranged as shown in figure Distance between centre of rod with mirror is x distance of end A of rod from mirror is u Then choose the correct option for x R 2 One More Correct Answer s A B B C u Image of end A will form on itself Image of end B will form on itself Lateral magnification of image is R R 21 0

English En Electromagnetic radiations of intensity 1 W m strikes on the surface of a substance which reflect 80 incident radiation back into same medium The radiation pressure on the surface of substance is Only One Correct Answer

For the given arrangement find out the path travelled by the incident ray within the slab in meter 2 m 2 3 O 3 2 3 2 2 2m air Google

PQR is an isosceles prism in which point 5 is the mid point of the face PQ The refractive index of the prism is 3 and its face QR is silvered O is point source A light ray has been sent from the source O to point S in such a way that it comes back to point O It is given that PR 2 CI Find the distance in cm of the source O from the point P 3 1 75 75

Two thin partially silvered glass plates are rigidly joined to form an angle 45 as shown in the figure A short light pulse is incident on the structure as shown The coefficient of reflection of light i e the fraction of light energy that is reflected by each surface is same and equal to p 1 2 Select the correct statement s A force applied by light pressure makes an angle 45 with x axis 7 B force applied by light pressure makes an angle tan 3 C force applied by light pressure makes an angle tan D Intensity of light reflected towards x direction by plate is equal to light 45 8 5 with x axis with x axis 45 x intensity of incid

ABCA is cross section of a transparent material of refractive index u is shown in figure One of its refracting surface AC is given by y x A ray of light travelling parallel to x axis is incident normally on face AB and refracted The minimum height h of the incident ray from point A to get refracted ray from surface AC is B h A A h u C h 4 1 4 7 y x B h 4 D h 3 2 3

D A ray is incident on a plane refracting surface as shown in the figure The incident ray vector is A 2 3 1 2 If the refractive index of the medium is 3 the angle of refraction will be Y 1 45 2 30 3 15 4 60 A O 3 Air X

There is an equiconvex lens of curvatu refractive index 1 5 kept before a plane refracting surface of index An object O is placed at a distance 2 R from the lens as shown in figure The distance of the final image from the lens will be 2R 1 2 R 2 1 R 3 2 1 R R

To read a poster on a wall a person with defective vision needs to stand at a distance of 0 4 m from the poster A person with normal vision can read the poster from a distance of 2 0 m Then the lens which can be used to correct his vision is O A concave lens of 1 0 D O A concave lens of 2 0 D O A convex lens of 2 0 D O A concave lens of 0 5 D Marks 4 1

A concave mirror of focal length 3 m is moving in the x y plane with a velocity 41 4 m s A point source S is also moving in the x y plane with a velocity 10 m s as shown in the figure At a given instant the object is at 5 m along the negative x axis from pole and 20 cm along positive y axis form the pole The pole is assumed to be origin at this instant Assuming paraxial approximation choose the correct option s 10m s S 37 A 20 cm 5m P Velocity of image with respect to mirror at the same instant is 91 18 m s Velocity of image with respect to mirror at the same instant is 181 5 m s Velocity of image with respect to ground at the same instant is 51 1 m s Velocity of image with respect to source at the same instant is 131 2 1 m s

6 The distance of a real object from the focus of a convex mirror of radius of curvature R is d Then One More Correct Answer s A B Review The distance of the image from the mirror is 4d R 2d R The distance of the image from the R 4d focus is

X Sorry Your Answer is Incorrect you scored 1 0 YOUR TIME ON AVG TIME OVERALL CORRECT Im 54s 3m 32s 24 TL Two plane mirrors are held at an angle lying between 2 radian and radian An object lies between the two mirrors The number of 7 11 images formed will be 1 2n 1 images 2 272 1 images n 1 images images

20 If an object of height 5cm was kept in front of the lens of power 1 D 1 at a distance 2 cm from it at what distance the image is formed and it nature would be i 0 66 cm virtual and erect ii 0 66 cm real and erect O iii 0 5 cm virtual and erect O iv 0 5 cm real and erect

Shown in the figure is a bi convex lens made of different transparent strips of two different refractive indices If the parallel rays of lig incident on the lens then select INCORRECT statement rays will intersect before focussing B rays will be focussed at two different points the lens may have four focal points different from each other DNone of the these

Light incident normally on a plane mirror attached to a galvanometer coil reflects backward as shown in figure A current in the produces a deflection of 3 5 of the mirror The displacement of the reflected spot of light on a screen placed 2m away is A m C 27 5 m 48 9 cm 24 5 cm D 12 2m 2m

When scattering sunlight is being caused by air molecule in sky it radiate energy B C Equally in all direction Maximum energy in the direction of oscillations No energy in the direction of oscillations Does not radiate energy at all

A sphere of refractive index 2 is kept in a space whose centre is O A ray is incident at point A of the sphere and after refraction at A it is internally reflected at point B then refracted at C and finally comes out from the sphere It is given that in then find the total deviation produced in the incident ray is minimum if the angle of incidence is given by i sin 1 the value of 1 B

A ray is incident on a curved spherical mirror of radius of curvatue 10 cm along a vector 1 21 2k The direction of normal at the point of incidence is along the vector 31 41 as shown in the figure The unit vector along the reflected ra Normal X 1 38 k 4 1 1 8 1 k 4 1 1 k 3 5 1 k 75

Assertion A concave lens is called a converging lens Reason Concave lens disperses the incoming light Both A and R are true and R is the correct a explanation of A b Both A and R are true but R is not the correct explanation of A C A is true but R is false d A is false but R is true

The rear view mirror of a car is a plane mirr or The car is at rest on a highway A truck is viewed at a distance of 200 m from the mirr or approaching the car at a uniform speed o f 10 ms When the truck just reaches the ca r the car starts moving and attains a unifor m speed of 25 ms Now a bus is moving in the opposite direction to the car at a speed of 20ms 1 The speed of the image of the bus in the mir ror with respect to the car in ms is A 5 B 20

An object is placed at a distance 3m from a thin equi convex lens at a point on its optical axis Its image is formed at 2 m from the lens as shown in the figure If lens is cut into two halves along the plane perpendicular to the optical axis and one of the halves is removed then the image is formed at a distance m from the lens Find K 24 K l Object image

At what angle must two plane mirrors be placed so that the incident and resulting reflected rays are always parallel to each other noils 1 0 3 60 2 30 90 4

c In an aquarium a fish 6 cm long is swimming directly towards the plane glass front If at a certain moment head of the fish is 18 cm behind the glass front find the apparent length of the fish as seen by a person looking through the glass Given R I of water 4 3

This section contains I Assertion Reason type question which has 4 choices A B C and D out of which ONLY ONE is correct A The sky appears blue due to atmospheric refraction R The sky appears dark instead of blue to an astronaut in space Only One Correct Answer A 9 C D Both A and R are true and R is the correct explanation of A Both A and R are true but R is not the correct explanation of A A is true but R is false A is false but R is true

A real object is placed at 5 CM from a concave Mirror A plane Mirror is set so that the virtual image formed by it coincide with the real image formed by concave Mirror If the plane Mirror is at a distance of 7 5 CM from the object then the focal length of the concave Mirror is Only One Conect Answer A 8 C 5 CM 2 CM 4 CM

A beam of white light falling on a glass prism gets split into seven colours marked I to 7 as shown in the diagram From given spectrum the numbers for corresponding colours that deviates more than yellow but less than indigo are Only One Correct Answer A 2 3 C 8 1 2 7 G 4 5 7 1234567 2 4 5 6 C

exhibit significantly different optical behavior without violating any physical laws Since n is negative it results in a change in the direction of propagation of the refracted light However similar to normal materials the frequency of light remains unchanged upon refraction even in metamaterials Choose the correct statement A The speed of light in the meta material is v c n B The speed of light in the meta material is C v C The speed of light in the meta material is V C D The wavelength of the light in the meta material m is given by Am dair n where Aair is the wavelength of the light in air

two plane mirrors P and Q are inclined at an angle of 75 degree to each other a ray of li ght is incident to mirror P at an angle of 40 degree what is the angle of reflection for the ray reflected from mirror Q

An object of height 3 0 cm is placed vertically on the principal axis of a convex lens When the object distance is 37 5 cm an image of height 2 0 cm is formed at a distance of 25 0 cm from the lens Next the same object is placed vertically at 25 0 cm from the lens In this situation the image distance v and height h of the image is according to the new Cartesian sign convention v 37 5 cm h 4 5 cm v 37 5 cm h 4 5 cm a b d v 37 5 cm h 4 5 cm v 37 5 cm h 4 5 cm

9 Using simple ray theory describe the mechanism for the transmission of light within an optical fiber Briefly discuss with the aid of a suitable diagram what is meant by the acceptance angle for an optical fiber Show how this is related to the fiber numerical aperture and the refractive indices for the fiber core and cladding An optical fiber has a numerical aperture of 0 20 and a cladding refractive index of 1 59 Determine a the acceptance angle for the fiber in water which has a refractive index of 1 33 b the critical angle at the core cladding interface 10 Marks

In the diagram shown all the velocities are given with respect to earth What is the relative velocity of the image in mirror 1 with respect to the image in the mirror 2 The mirror 1 forms an angle with the vertical I A 2Vsin28 B 2Vsin C 2V sin2 D none

In one book it is written that optical fibr es are fabricated such that the light refl ected at one side of inner surface strike s the other at an angle larger than the c ritical angle explain this how with dia 22 a

Three lenses A B and C are placed in contact The magnifications produced by the lenses are individually 2 3 and 4 respectively The net magnification produced by the lens combination is O 12 24 10

I wo plane mirrors are placed perpendicular to each other as shown A ray of light is incident on one mirror at 75 What will be th e angle of reflection from the second mirror Complete the ray diagram and show all the mathematical steps Two plane mirrors are placed perpendicular to each other as shown A ray of light is incident on one mirror at 75 What will be the angle of reflection from the second mirror Complete the ray diagram and show all the mathematical steps

The image of a small dot fixed on the wall of a room is to be obtained on the opposite wall 4 m away by means of a large convex lens What is the maximum possible focal length of the lens required for the purpose 2 m 03m 4 m

A convex lens produces an inverted image of size 1 4 cm The size of object is 0 7 cm What is magnification in this case O 1 2 sec 0 2

A spherical thick shell made of transparent material is cut along its chord as shown The smaller part will A behave like a converging lens in air C behave like a parallel glass slab in air B behave like a diverging lens in air D behave like a prism in air

Focal length of a convex lens is equal to 10 cm The power of lens is equal to 0 1 D 10 D se 01D

Among the following choose the correct option s Optically denser medium always has a larger mass density Turpentine is optically denser than water Mass density of turpentine is higher than water Both 1 and 2

There is a convex mirror of radius of curvature 20 cm The image of a point at a distance 100 cm from the pole of mirror on its axis will be formed at 21 11 cm 100 11 cm O 1 11 cm

An object is placed at a distance 20 cm in front of a concave mirror of focal length 40 cm Find the magnification of the image formed by the mirror O 1 02 3

Light from a point source in air falls on a spherical glass surface n 1 5 and radius of curvature 10 cm The distance of the light source from the glass surface is 50 cm At what distance from the centre of the sphere is the image formed O 10 cm 20 cm 30 cm O 5 cm

Suppose that the upper half of a convex lens is covered with an opaque non reflective material what will be the effect on the image of an object placed in front of the lens Image will be shifted along principal axis Image will be shifted parallel to the principal axis The intensity of the image will decrease The intensity of the image will increase