Wave Optics Questions and Answers

In a Young s double slit experiment using light of wave length a thin piece of Plexiglas having index of refrac tion n covers one of the slits If the center point on the screen is a dark spot instead of a bright spot what is the minimum thickness of the Plexiglas

Consider N coherent sources described as follows E Eosin wt b E Eosin wt 24 E3 Eosin wt 36 EN Eo sin wt No Find the minimum value of for which ER E1 E2 E3 Ey is zero 3

A beam of light in air hits a stack of three slides with thicknesses of 2d d and d and refractive indexes of 2n n and n respectively at an incident angle of 600 as seen in the figure O 30 O None of these 90 2d O 60 O 120 d 60 d What is the angle 0 when the light exits the stack 8 no 2n n n no

Interference effects are produced at point P on a screen as a result of direct rays from a 500 nm source and reflected rays from the mirror as shown in Figure P37 52 Assume the source is 100 m to the left of the screen and 1 00 cm above the mirror Find the distance y to the first dark band above the mirror Source Mirror Viewing screen P

Two narrow parallel slits separated by 0 850 mm are illumi nated by 600 nm light and the viewing screen is 2 80 m away from the slits a What is the phase difference between the two interfering waves on a screen at a point 2 50 mm from the central bright fringe b What is the ratio of the intensity at this point to the intensity at the center of a bright fringe

When a liquid is introduced into the air space between the lens and the plate in a Newton s rings apparatus the diameter of the tenth ring changes from 1 50 to 1 31 cm Find the index of refraction of the liquid

When illuminated four equally spaced parallel slits act as multiple coherent sources each differing in phase from the adjacent one by an angle Use a phasor diagram to determine the smallest value of o for which the resultant of the four waves assumed to be of equal amplitude is zero

Suppose the slit openings in a Young s double slit experi ment have different sizes so that the electric fields and intensities from each slit are different With E1 E01 sin wt and E2 E02 sin wt d show that the resultant electric field is E Eo sin wt 0 where Eo E E2 2E01E02 cos and For sin d

The two speakers of a boom box are 35 0 cm apart A single oscillator makes the speakers vibrate in phase at a frequency of 2 00 kHz At what angles measured from the perpen dicular bisector of the line joining the speakers would a distant observer hear maximum sound intensity Minimum sound intensity Take the speed of sound as 340 m s

In a double slit arrangement of Figure 37 5 d 0 150 mm L 140 cm 643 nm and y A 1 80 cm a What is the path difference 8 for the rays from the two slits arriving at P b Express this path difference in terms of A c Does P correspond to a maximum a minimum or an interme diate condition

The angular width of the central maxima of the diffraction pattern in a single slit of width a experiment with A as the wavelength of light is 1 2 3 Correct Answer 3 our Answer 2 tatus incorrect 3X 2a 2a 2X a a

40 Two coherent planeJight waves of equal amplitude makes a a small angle 1 with each other They fall almost normally on a screen If is the wavelength of light waves the fringe width Ar of interference patterns of the two sets of waves on the screen is 2 b L O A 20 d a

In Young s double slit experiment two wavelengths of light are used simultaneously where 2 22 In the fringe pattern observed on the screen 26 Fi 1 maxima of wavelength 2 can coincide with minima of wavelength 2 2 fringe width of 2 will be double that of fringe width of and nth order maxima of 2 will coincide with 2nd order maxima of 2 3 nth order minima of 2 will coincide with 2nth order minima of 2 4 none of these

Q3 Two coherent beams of light having intensities I and 41 interfere to produce fringe pattem on screen The phase difference between beams is 1 2 at point A and at point B Then t difference between resultant intensifies at A and B is O A 21 8 51 O c 41 D 71

Q4 Ablock of transparent material is shined by a laser beam along the surface as shown in figure One half of the beam goes straight to detector while other half travels inside the block a reaches detector At detector the time delay between the arrival of two beams is 6 3 nanosecond The refractive index of the material is 1 55 1 63 O C 1 75 1 42 0 0 0 0 A B D R 3 0m Detector

600 nm and2 b Newton s rings are formed with a source of light containing two wavelengths 450 nm It is founded that mth dark ring due to coincides with the m 1 th dark fringe of A2 If the radius of curvature of the curved surface is 90 cm find the diameter of mth dark ring of A 5 5

Young s double slit experiment a point source is placed on a solid slab of refractive index 6 5 at a distance of 2 mm from two slits spaced 3 mm apart as shown and at equal distance from both the slits The screen is at a distance of I m from the slits Wavelength of light used is 500 nm K S 2 mm 26 l 6 5 3 mm The central maxima is at 6 The central maxima is at 1 Im m below O m below O 600 The order of the fringe formed at O is 750 B If a film of refractive index 1 8 is to be placed in front of S so that central maxima is formed where 200th maxima was formed Then the thickness of film is 1

diffraction grating with 380 lines mm is 1 55 m front of a screen Part A What is the wavelength of light whose first order maxima will be 16 4 cm from the central maximum on the scre Express your answer to three significant figures VAX SWD

3A 4A Read More Two coherent light sources P and Q are at a distance 3A from each other as shown in the figure The distance from Pon the x axis at which constructive interference may take place is y axis x axis and 4 out of is cor

n a standard YDSE arrangement d 3 mm D 1 m and wavelength 1 mm Plane wave is incident normally on the slits as shown Then L Screen 1111 A B C D y coordinate of first order maxima is 15 15 cm y coordinate of first order maxima is 35 35 cm Number of maxima excluding at infinity on screen is 5 Number of minima on screen is 6

10 Three slabs A B and C are placed in front of slits in YDSE as shown in figure Refractive index of slabs A B and C are 4 3 5 3 and 8 3 respectively and thickness of A B and C are 2 mm 1 mm and 1 5 mm respectively A liquid of refractive index 2u 3 is filled between slits and screen A monochromatic light of wavelength 5000 is incident on the slits If the central bright fringe is obtained at C then find the value of u S 2 IS atno 8 16 3

ash me ans violet dia hai hat is correct In white light interference nearest to the central bright fringe will have which of the following colour 1 violet 2 yellow red 4 green EW00047

For a transparent medium relative permeability and permittivity u and e are 1 0 and 1 44 respectively The velocity of light in this medium would be NEET 2019 Odisha 2 2 5 108 m s 4 2 08 108 m s 1 4 32 108 m s 3 3 x 108 m s o

Light of wavelength 6000 is incident on a thin glass plate such that angle of refraction into the plate of 60 If the smallest thickness of plate which makes it appear dark by the reflection is 4 x 107 m What is the refractive index of glass plate 1 5 3 2 3 2 3 PAN 413 4 2

When the angle of incidence on a material is 60 the reflected light is completely polarized The velocity of the refracted ray inside the material is in ms 1 3 108 3 3 108 3 4 0 5 108 2 108

slits are of unequal width e slit on screen is four times that only due to the other The screen is placed along axis as shown in figure screen distance between slits is d and that between the lits is D Match the statements in Column I with results lumn II D Column I i The distance between two points on the screen having equal intensities such that intensity at those points is abc d 1 th of maximum intensity 9 O ii The distance between two points on the screen having equal intensities such that intensity at those points is 3 th of maximum intensity int Screen a bcd iii The distance between two points on the screen having equal intensities such that intensity at those points is b Column II D 3d th of maximum intensity 9 mensity b d iv The distance between two d points on the screen having equal intensities such that D d C 2D d 3D d

39 A plane wavefront 6 x 10 7 m falls on a slit 0 4 m wide A convex lens of focal length 0 8 m placed behind the slit focuses the light on a screen What is the linear diameter of second maximum a 6 mm c 3 mm b 12 mm d 9 mm

ang s double slit experiment is performed in air central maxima is obtained on screen at some position Two slabs are placed in front of two slits S and S The slab placed in ckness t and of refractive index 1 6 and the slab placed in front of S is of refractive index 1 4 Find its thickness if position of central maxima remain unchanged on putting two s 1 51 1 41 1 61 8t

5 Which of the following sentences are correct 2 Points To observe the interference due to thin film is illuminated by extended source thickness of the film should be much much smaller than coherence length of source optical path difference between superposing waves must be much

4 A soap film of RI 1 33 and thickness t is illuminated by light of wavelength lamda incident at an angle 60deg The minimum thickness to observe the dark band at viewing angle 60deg for wavelength lamda is 3 Points lamda 5 x 10 5 cm 2 5 x10 5 cm 2 5x10 7 cm O 0 25micron

Young s double slit experiment is performed in air central maxima is obtained on screen at some position Two slabs are placed in front of two slits S and S The slab placed in front of S is of thickness t and of refractive index 1 6 and the slab placed in front of S is of refractive index 1 4 Find its thickness if position of central maxima remain unchanged on putting two slabs 1 1 5 t 2 1 4 t 3 1 6 t 4 S

Two coherent sources are 0 3 mm apart They are 1 m away from the screen The second dark fringe is at a distance of 0 3 cm from the centre Distance of fourth bright fringe from the centre is Only one correct answer A 0 6 cm B C 0 8 cm 1 2 CM i

38 In Fresnel diffraction if the distance between the disc and the screen is decreased the intensity of central bright spot will a biqu a Increase b Decrease igi c Remain constant fide d None of these d

Two coherent light sources P and Q are at a distance 3A from each other as shown in the figure The distance from Pon the x axis at which constructive interference may take place is y axis 3 2 4 3 4 x axis

Suppose that reflected white light is used to observe a thin transparent coating on glass as the coating material is gradually deposited by evaporation in a vacuum Describe color changes that might occur during the process of building up the thickness of the coating

111 Image of sun formed due to reflection at air water interface is found to be very highly polarised Refractive index of water being 4 3 find the angle of sun above the horizon A 34 70 C 37 30 B 36 9 D 35 8

n a young s double slit experiment slits are illuminated by a monochromatic source of wavelength 6000 A and fringes ar obtained If screen is moved by a distance of 5 cm towards slits change in fringe width is 3 x 10 5 m Then separation between the slits will be 1 mm 1 2 mm 1 5 mm 1 63 mm

Total internal reflection can take place only if Select an answer A B C D light goes from optically rarer medium to optically denser medium 21 light goes from optically denser medium to rarer medium C the refractive indices of the two media are close to each other the refractive indices of the two media are widely different

A point source of light at the surface of a sphere causes a parallel beam of light to emerge from the opposite surface of the sphere The refractive index of the material of the sphere is Considering sin 0 Write an answer

13 Which of the following sentence is correct 1 Point O O Condition of constructive and destructive interference for transmitted and reflected light from a thin film are same Condition of constructive and destructive interference for transmitted and reflected light from a thin film are complementary

Two identical photo cathodes receive light of frequencies f1 and f2 If the velocities of the photo electrons of mass m coming out are respectively v and v then A V1 V2 D v v 2h 2h B V V f1 f2 m 2h f f m m 1 2 2h C V V2 m 1 2 f f

In Young s double slit experiment one of the slit is wider than other so that the amplitude of the light from one slit is double of that from other slit If I be the maximum intensity the resultant intensity when they interfere at phase differ ence is given by I a 1 20 2 m1 2 cos 3 1 8 cos 9 2 1 b b d m1 4cos 5 4 5 cos

In YDSE an electron beam is used to obtain interference pattern If the speed of the electron decreases then Distance between consecutive fringes decrease Distance between consecutive fringes increases Distance between consecutive fringes remains same More information is required

The slits are 1 mm apart from each other and illuminated with a light of wavelength 5 x 10 7 m If the distance of screen from slits plane is 1 m then distance of third dark fringe from central maxima will be 1 25 mm 2 50 mm 3 75 mm 0 75 mm

Light waves from two coherent sources of intensity ratio 81 1 produce interference What is the ratio of maximum and minimum intensity in interference pattern 56 25 16 36 25

Light of wavelength 500 nm is incident on two slits separated by 1 mm in YDSE What is width of each bright band if screen is 1 m away from slit planes 0 2 mm O 0 25 mm O 0 3 mm 0 5 mm

In YDSE yellow light of wavelength 6000 produced fringes of width 0 8 mm If the source is replaced by another monochromatic source of wavelength 7500 and separation between slits is same the fringe width becomes 1 mm 0 5 mm 0 6 mm 0 4 mm

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

ALLE A horizontal light ray passes through a prism 7 u 1 5 of angle 4 Further it is incident on a plane mirror M that has been placed vertically By what angle the mirror is rotated so that the ray after reflection becomes horizontal A 1 1 2 2 FM 3 4 4 8

If the angular dispersion produced by a prism is e for a wavelength 4000 then the angular dispersion for a wavelength 8000 may be A O e O 0 O O 8 38