Wave Optics Questions and Answers

0 Two periodic waves of intensities I and 1 pass through a region at the same time in the same direction The sum of the maximum and minimum intensities is a c I I b 2 1 1 d 2008

ALLEN In an AC circuit V and I are given by 39 V 150sin 150t V and 1 150 sin 150t A A The power dissipated in the circuit is 1 Zero 2 5625W 3 150W 4 106W V 150sin 1501 V 1 150 sin 150t A 1 Zero 2 5625W 3 150W 4 106W

A disc is placed on the surface of pond with liquid of refractive index 3 A source of light is placed 4 m below the surface What is minimum area of the disc so that light does not come out of liquid O 28 26 m O 42 4 m O 32 62 m O 32 6 m

Q 31 Option 1 2 Your Answer 3 Option 2 3 Option 3 4 Option 4 Figure shows two coherent sources S S vibrating in same phase AB is an irregular wire lying at a far distance from the sources S and S Let 10 10 ZBOA 0 120 How many bright spots will be seen on the wire including points A and B d IS I ok of force move from south pole to north pole IS B

Laser light of wavelength 630 nm incident on pair of slits produce an interference pattern where bright fringes are separated by 8 1 mm Another laser light produces interference pattern where bright fringes are separated by 7 2 mm What is wavelength of second light O 560 nm O 615 nm O 415 nm O 712 nm

In single slit diffraction experiment first minima of red light A 660 nm coincides with first maxima of other wavelength A2 What is the value of 2 O 440 nm O 470 nm O 550 nm O 690 nm

Match the columns and select the correct option from the codes given below Column l Column Il i Focal length of convex lens ii Object placed between C and F by convex lens iii Twinkling of a star A i a ii b iii c C i a iii b ii c a Real Inverted Magnified b Due to refraction c Positive B iii a i b ii c D ii a iii b i c

In a LLyod s mirror set up for interference of waves of frequency 6 x 10 4 1 emitted from point source S Distance SO OA AC are 1 mm 50 cm and 50 cm respectively Then the number of dark and bright fringes obtained on the screen will be S 0 O O O Mirror SCREEN C Dark 4 Bright 4 Dark 4 Bright 5 Dark 5 Bright 4 Dark 5 Bright 5

Monochromatic light of frequency is 6 0 1014 Hz produced by a laser The power emitted is 2 x 10 W The number of photons emitted on the average by the source per second is 1 5 1014 3 5 1016 AIPMT Prelims 2007 2 5 1015 4 5 1017

1 A glass plate u 1 5 of thickness t is placed in front of one of the slits in a double slit experiment What should be the minimum thickness t which will make the intensity at the center of the fringe pattern zero wavelength of light used 2 2 3 24 22 4 2

In a Young s double slit experiment the slits are placed 0 320 mm apart Light o wavelength 500 nm is incident on the slits The total number of bright fringes that ar observed in the angular range 30 0 30 is A 640 C 321 B 320 D 641 7 19 pm

Two beams of light having intensities 41 and 9 interfere to produce an interference pattern on a screen The phase difference between the beams is 2 at point A and at point B Then the difference between the resultant intensities at points A and B on the screen is NI find N 12

Two identical sources P and Q emit light waves in same phase and of same wavelength Distance between P and Q is 32 The maximum distance from P along the x axis at which a minimum intensity occurs is given by k times find k PL X 8 75

Q No 20 View In English Assuming human pupil to have a radius of 0 25cm and a comfortable viewing distance of 25cm the minimum separation between two objects that human eye can resolve at 500 n wavelength is 1 2 3 Correct Answer 4 Status unattempted 100 m 300 m 1 m 30 5 m V

The light waves having wave equations y 10Sin ot kx and y 5Sin kx oot interfere The ratio of maximum to the minimum intensity of light in the interference pattern is 1 9 1 2 3 1 3 2 1 4 81 1

Why in the below question we are not using the formula which is given below after finding the phase difference The below given formula is used for finding the resultant i ntensity Please say what are the difference between these two for mula 1 the intensity at the maximum in a young double slit experiment is lo distance between two slits is d 5A where A is the wavelength of light used in front of one of the slit on the screen placed at a distance D 10d 20 03 2017 4074 A4988 5 D Path difference Ax sp sp 5x D D 52 10d 10d Vi 52 501 507 50 25 50 25 2 4 Hence phase diff A Now 1 1 cos cos

8 Consider the arrangement shown in figure distance D is large compared to the seperation between the slits A monochromatic beam of light c wavelength falls on the slit as shown Find th distance x at which the first order bright fringe formed 1 3 Incident ray AD d 3 AD S d l D ak 2 D 2 D d PA O X screen D d

In a double slit experiment green light 5303 falls on a double slit having a separation of 19 44 m and a width of 4 05 m The number of bright fringes between the first and the second diffraction minima JEE Main 2019 Online is 1 09 2 10 4 05 3 04

In a YDSE d 1 mm 6000 and D 1 m The slits produce same intensity on the screen The minimum distance from central maximum where intensity is 75 of the maximum intensity is Only one correct answer A 0 45 mm B C D 0 40 mm 0 30 mm 0 10 mm

In a standard YDSE set up a slab of thickness t refractive index is placed in front of the upper slit Other symbols have usual meaning 1 11 III IV 1 Column 1 2 D 3 D D D 10 3 2 x 10 3 5 x 10 4 4 x 10 3 1 i P i II ii Q ii III iii R iii iv Column 2 t 1 m 1 6 t 1 5 m 1 3 t 2 m 1 6 If the intensity at central maxima is lo in which of the following case intensity at the centre of the screen is zero t 2 5 m 1 4 Question Type Single Correct Type Column 3 P 400 nm Q X 500 nm R 600 nm S 700 nm

48 When ordinary light of intensity 100 unit is incident on a polariser The output intensity will be Caffarell Gidl Gafah S100 at faria aldi ari 3 75 2 50 4 100 1 25 19 A hodu is performing simple harmonic motion with amplitude a and time period T Variation of its

1 9m 2 12m 3 15m 4 18m Determine the angular separation between central 8 maximum and first order maxima of the diffraction pattern due to a single slit of width 0 25 mm when light of wavelength 5890 A is incident on it 1 3 534 10 rad 2 2 35 10 rad 4 15 8 10 3 1 47 10 rad rad 1 9m 2 12m ET 1 3 534 10 3 1 47 10 5890 fere q nafara for a feat caufa q rad 3 15m rad 4 18m 0 25 mm at fada f 2 2 35 10 rad 4 15 10 nd

Two events are separated by a distance of 6 x 105 km and the first event occurs 1 sec before the second event The interval between the two events a is time like c is space like b is light like null d cannot be determined from the information given

Match the corresponding entries of Column 1 with Column 11 Where m is the magnification produced by the mirror Column 1 A m 2 1 2 C m 2 B m 1 D m 2 Column II p Convex mirror C q Concave mirror r Real image Virtual image a A p and s B q and r C q and s D q and r b A r and s B q and s C q and r D p and s c A q and r B q and r C q and s D p and s d A p and r B p and s C p and q D r and s S

Two polarising sheets are placed with their plane parallel so that light intensity of transmitted light is maximum Through what angle must either sheet be turned so that light intensity drops to half of maximum value 30 45 135 Both 2 and 3 are correct

5 In single slit diffraction wavelength used is 5000 A slit width is 0 2 mm and distance between slit and screen is 2 m The distance of first secondary minimum from principal maximum is 1 2 5 mm 2 3 mm 3 4 5 mm 4 5 mm

9 Two wave are represented by the equatio y a sin ot and a cos wt The first wave 1 Leads the second by 2 Lags the second by 92 3 Leads the second by 4 Lags the second hu T TC 2 wesenspers

E 3 3 3 In a double slit experiment n fringes are observed to be formed on a screen placed at a distance D from the slits when light of wavelength is used Now the screen starts moving from rest with constant acceleration a Then the time after which the first maxima disappears from screen and the direction of motion of screen are respectively 2D n 1 1 2 3 tionpaper 2D n 1 2D n 1 2D n 1 a away from slits towards slits away from slits towards slits

56 A light source emitting a light of frequency 6 1015 Hz is moving away from an observer with a speed of 4 m sec Then the apparent change in the frequency of light as observed by the observer will be 1 8 107 Hz 3 2 107 Hz 2 4 107 Hz 4 8 108 Hz

0 A ray of light is incident on a glass plate at the polarising angle 57 Then Given tan57 1 The reflected ray and transmitted ray both will be completely polarised 2 The reflected ray will be completely polarised 57 and the transmitted ray will be partially polarised 3 The reflected ray will be partially polarised and the transmitted ray will be completely polarised 1 Which of the following phenomena is not exameetquest 4 The reflected and transmitted both rays will partially polarised

Wave Optics 37 When angle of incidence on a material is 60 the reflected light is completely polarized The velocity of the refracted ray inside the material is 1 3 x 10 m s 2 3 x 10 m s 3 1 5 10 m s 38 Light from n incoherent sources of intensity 1 21 31 nl are super imposed in a region Resultant intensity at a point in the region of superposition will be 1 Zero 2 n 3 n n 1 2 4 Can not be determined 39 A spaceship is moving with a velocity 10 m s towards a star that emits radiations of wavelength 6000 A The wavelength of radiation received by the crew in the spaceship will be 1 4000 A 3 5500 A 4 x 10 m s 2 1 40 Two polariser have polarising directions parallel to each other so as to transmit maximum intensity By keeping one of the polariser fixed other rotated through different angles 0 The graph which represents the variation of transmitted intensity versus is mo 2 4500 A 4 6500 A 3 2 m Atmo 41 A star is emitting radiation of wavelength 5000A The star is approaching the earth with a velocity of 1 5x105 m s The change in the wavelength of the radiation as received on the earth is 1 25 A 2 100 A 4 Zero 3 2 5 A 42 When light of particular wavelength falls on a plane surface at an angle of incidence of 60 the reflected light becomes completely plane polarised The refractive index and the critical angle of the material are respectively 43 0 44 1 3 sin 3 3 sin 3 4 3 sin In a double slit experiment n fringes are observed to be formed on a screen placed at a distance D from the slits when light of wavelength is used Now the screen starts moving from rest with constant acceleration a Then the time after which the first maxima disappears from screen and the direction of motion of screen are respectively 2D n 1 1 2D n 1 heetquestion paper 2D n 1 2D n 1 2 away from slits towards slits away from slits Aakash Institute towards slits sin Between two coherent waves phase difference at a particular position is 1 Ap x A6 t 2 A t constant 3 Ap x 4 t constant 4 Ap x constant 45 Two coherent waves of intensities I and 41 superpose then the maximum and minimum intensities produced are 1 51 and 31 3 91 and 31 2 91 and 1 4 51 and 1 46 In young s double slit experiment the y co ordinates of central maxima and 10th maxima are 2cm and 5cm respectively When the YDSE apparatus is immersed in a liquid of refractive index 1 5 the corresponding y co ordinates will be 1 2cm 7 5cm 2 2cm 4cm 3 3cm 6cm 4 3cm 7 5cm 47 In young s double slit experiment the two slits are d distance apart Interference pattern is observed on a screen at a distance D from the slits A dark fringe is observed on the screen directly opposite to one of the slit The wavelength of light may be

4 When a film of transparent material of thickness 2 5x10 3 cm is placed over one of the slit in YDSE The fringe pattern shifts by a distance equal to 20 fringes widths The R I of material of the film is 5000 A 1 1 25 3 1 40 In VD with light 2 1 35 4 1 50

E D 18 A parallel beam of mono chromatic light o wavelength 5000 A is incident normally on a single narrow slit of width 0 001 mm The light is focused by a convex lens on a screen placed on the foca plane The first minimum will be formed for the angle of diffraction equal to 1 30 3 15 2 60 4 0

In young s double slit experiment the y co ordinates of central maxima and 10th maxima are 2cm and 5cm respectively When the YDSE apparatus is immersed in a liquid of refractive index 1 5 the corresponding y co ordinates will be 1 2cm 7 5cm 3 3cm 6cm 2 2cm 4cm 4 3cm 7 5cm

The figure shows two points source which emit light of wavelength in phase with each other and ar at a distance d 5 52 apart along a line which is perpendicular to a large screen at a distance L from t cente of the source Assume that d is much less than L Which of the following statement s is are correct excluding fringe at infinity B C S L Screen Ty 0 0 Only Only six bright fringes appear on the screen Point y 0 corresponds to bright fringe five bright fringes appear on the screen Point y 0 corresponds to dark fringe

Between two coherent waves phase difference at a particular position is 1 A6 x A6 t 2 A t constant 3 Ap x A6 t constant

In YDSE distance between two slits is 1 mm distance of screen from two slits is 4 m If light of wave length 500 nm is used in experiment then what is distance in mm between 3rd maxima and 5th minima formed on same side of the central maxima

3 45 4 50 32 When a thin film is illuminated by a parallel bear of 6000 A of light wavelength 7 fringes are observed in a certain region of the film How many fringes will be observed in the same region of the film if light of wavelength 420 A is used 1 6 2 10

uations y 7 6 interfere m intensity of In Youngs double slit experiment if the widths of the slit are in the ratio 4 9 ratio of intensity of maxima to intensity of minima will be width of slit is directly proportional to amplitude of interfering waves 1 25 1 2 9 4

x 10 7 d on a s The bright 2 2 20 In Young s double slit experiment interference pattern is found to have an intensity ratio between bright and dark fringes as 9 Then amplitude ratio of the wave reaching the screen from two sources is er 2 2

3 It is found that when waves from two identical coherent sources superpose at certain point with same individual intensity then the resultant intensity is equal to the intensity of one wave only This means that phase difference between the two waves at that point is 1 Zero 3 2 3 2 1 3 4 T

Two beams A and B of plane polarised light with mutually perpendicular planes of polarisation are seen through a polaroid From the position when the beam A has maximum intensity and beam B has zero intensity a rotation of polaroid through 60 makes the two beams appear equally intense If the initial intensities of the two beams are I and I 10 respectively then equals 18 1 3 2 4 3 PIN N W 2

8 In a YDSE how many maxima can be obtained o screen excluding central maxima on both sides a central fringe if 2000A and d 7000A 1 12 2 6 3 18 4 9

9 A beam of unpolarised light passes through a tourmaline crystal A and then it passes through a second tourmaline crystal B oriented so that its principal is parallel to that of A The intensity of the emergent light is Now B is rotated by 45 about the ray The emergent light have intensity 3 2 11 2012 4

2 A soap bubble 250nm thick is illuminated by white light The index of refraction of the soap bubble is 1 36 Which wavelength is missing in range of visible light for reflected rays 1 300mm 2 600mm 3 400mm 4 680mm

6 The minimum thickness of a soap bubble film 1 33 that results in constructive interference in the reflected light if the film is illuminated with light whose wavelength in free space is 600 nm is 2 225 26 nm 1 112 50 nm 3 400 nm 4 176 5 nm

4 Two slits are separated by a distance of 1 mm are illuminated with red light of wavelength 6 5 x 10 7 metre The interference fringes are observed on a screen placed 1 metre away from the slits The distance between 3rd dark fringe and fifth bright fringe is equal to 1 0 65 mm 3 323 m 2 1 63 mm 4 468 mm

An unpolarized light passes through 2 polarizer If the intensity of the transmitted light is 20 that of 11 The the original light what is the angle between the 5 0 transmission axes of the 2 polarizing sheets resa 1 Cos 0 3 2 Cos 0 4 3 Cos 0 6 4 Cos 0 7 1 3

2 10 cm 4 2 cm 3 1 cm An equiconvex lens of focal length f is cut into two equal parts In 1st case it is cut perpendicular to principal axis and in 2nd case it is cut parallel to principal axis Then the focal length of both piece in the two cases will be respectively 1 2f f 11 3 2 2f 2f 4 F

A Youngs double slit experiment is immersed in a liquid of refractive index The slit plane touches the liquid surface A parallel beam of monochromatic light of wavelength with respect to air is incident normally on the slits Choose the correct statement s of the following screen d 21 1 cos Liquid S JAYA YEVA A The fringe width is B If one of the slits S is covered by a transparent slab of refractive index and thickness t the new position of the central maximum will shift up by 2 1 tD d C The ratio of the intensities at O in the conditions of the option A and option B is 17 1 D If a slab of thickness t and refractive index 3 is introduced in front of S and S is also covered by a slab of thickness t and refractive index as shown in the figure then for relation 1 the central maxima will be at O