Wave Optics Questions and Answers

5 Two polaroids are crossed If now one of them is rotated through 30 and unpolarised light of intensity lo is incident on the first polaroid then the intensity of transmitted light will be 10 3 0 a b c 3 d 8

Due to effect of interfernce floating oil layer in water is visible coloured due to observation of this event the thickness of oil layer should be 1 10 nm 4 10 mm 2 0 1 m 3 1 mm

7500 and X In Young s double slit experiment the slits are 2mm apart and are illuminated with a mixture of two wavelength 9000 A At what minimum distance from the common central bright fringe on screen 2 m from the slits will a bright fringe from one interference pattern coincide with a bright frin from the other

In an interference pattern at a point we observe the 16th order bright fringe or maxima for 7200 What order will be visible here if the source is replaced by light of wavelength 4800 1 12 2 24 3 36 4 16 Main difference between interference and diffraction is 1 Diffraction is due to interaction of light from the same wavefront whereas interference is the

If intensity of principal maximum in Fraunhof single slit diffraction is Then intensity second order secondary maxima is 1 2 3 lo 62 5 ol lo 22 5 4

Bichromatic light of wavelength 2 3000 and 5000 is used in YDSE It is found the n bright fringe of overlap with n Bright fringe of 22 If D 1 m and d 1 mm then find distance of overlapping point from center 1 2 5 mm 2 0 9 mm 4 2 mm 3 1 5 mm

The wavelength of a distant star is 5700 and the spectral light has a shift 1 9 towards red end then the velocity of star relative to earth will be 1 5 x 105 m sec 3 1 8 105 m sec 2 2 105 m sec 4 1x 105 m sec

A convex lens of power P is immersed in water how will its power change 2 1 1 Increases 2 Decreases 3 Remains unchanged Tinig 4 Increases for red colour and decreases for blue 08 to siprie colour GITT ds

Light of wavelength is incident on a slit of width d The resulting diffraction pattern is observed on a screen at a distance D The linear width of the principal maximum is then equal to the width of the slit if D equals 1 121 G d 2 4 22 d 22 2

nm 1 Two coherent monochromatic point sources S and S of wavelength placed symmetrically on either side of the center of the circle as shown The sources are separated by a distance d 1 8 mm This arrangement produces interference fringes visible as alternate bright and dark spots on the circumference of the circle The angular separation between two consecutive bright spots is A0 Which of the following options is are correct S P d 10 S P2 A A dark spot will be formed at the point P2 B At P the order of the fringe will be maximum C The total number of fringes produced between P and P2 in the first quadrant is close to 3000 D The angular separation between two consecutive bright spots decreases as we move from P to P along the first quadrant

The speed of light in an isotropic medium depends on 1 the direction of propagation 2 the wavelength 3 its intensity

104 In Young s double slit experiment D d distance between the slit D distance of screen from slits At a point P on the screen the resulting intensity is equal to the intensity due to individual slit Io The the distance of point P from the central maximum is Take 6000 1 2 mm 3 0 5 mm 2 1 mm 4 4 mm

Two beams of light having intensities I and 41 interfere to produce a fringe pattern on a screen The phase T difference between the beams is 2 PEEDHOD at a point A and it at a point B Then the difference between resultan intensities at A and B is 1 21 3 51 2 41 4 71

1n Young s double slit experiment the intensity of light at a point on the screen where the path difference is K being the wavelength of light used The intensity at a point where path difference is 4 1 K 3 K x c 2 K 4 4 zero will be

c 61 d Two coherent sources P and Q produce interference at point A on the screen where there is a dark band which is formed between 4th bright band and 5th bright band Wavelength of light used is 6000 The path difference between PA and QA is a 1 4 x 104 cm c 4 5 x 104 cm b d 4 2 7 x 10 6 2 10 4 cm cr cm MHT CE

The sound emitted from the siren of an ambulance has frequency of 1500 Hz The speed of sound is 340 m s Calculate the difference in frequencies heard by a stationary observer it the ambulance initially travels towards and then away from the observer at a speed of 30 m s

In order that a thin film of oil floating on surface of water should show colours due interference the thickness of the oil film sho be of the order of 1 100 2 10 000 3 1 mm 4 1 cm

A beam of natural light falls on a system of 5 polaroid s which are arranged in succession such that the pass axis of each polaroid is turned through 60 w r t the preceding one The fraction of incident light that passes through the system 1 40 Check all that apply A B C 1 2 ST22 512 3 1 256 4 1 128

A plane mirror and a concave mirror of radius o curvature 60 cm are placed facing each other with a point object at the center of them If the image formed by first reflection at the spherical mirror and then at the plane mirror coincides with the objec then the separation in cm between two mirrors wi be

A double slit of separation 1 5 mm is illuminated by white light between 4000 8000 On a screen 120 cm away coloured interference pattern is formed If a pinhole is made on this screen at a distance of 3 0 mm from the central white fringe some wavelengths will be absent in the transmitted light Find the second longest wavelength in which will absent in the transmitted light

In Young s double slit experiment to increase the fringe width 1 the wavelength of the source is increased 2 the screen is moved towards the slits 3 the source is moved away from the slits 4 the slit separation is decreased

In Young s double slit experiment using a monochromatic light of wavelength the path difference in terms of an integer n corresponding to any point having half the peak intensity is 1 2n 1 2 2 2n 1 2 3 2n 1 A 4 2n 1 16

Transverse nature of light was confirmed by the phenomenon of 1 refraction of light 3 dispersion of light 2 diffraction of light 4 polarisation of light

JEL 43 A source of light of wavelength 5000A is placed at one end of a table of 200 cm long and 5 mm above its reflecting surface Find the fringe width of the interference pattern formed on the screen 22 F Sun B D 200 cm Screen frings the w then will ref 89 In fri cer W 60 W fr 0 01 Cm 2 0 02 Cm 3 0 03 Cm 4 0 04 Cm 61 54 In a double slit experiment instead of taking slits of equal widths one slit is made twice as wide as the other Then in the interference pattern 4 The intensities of both the maxima and the

2 wa intensity ratio of the sources 4 distance between the sources When viewed in white light soap bubble shows colours because of 2 Scattering 3 Diffraction 4 Dispersion light in Young s experiment what will If torch is used in place of monochromatic 1 Fringe will occur as from monochromatic happen source lamp b w d 37 2 Fringe will appear for a moment and then it will disappear No fringes will appear WI Only bright fringe will appear nYDSE the number of times the intensity f the central bright band greater than the idual intensity of the inte torf

3 In an interference experiment monochromatic light is replaced by white light we will see 1 Uniform illumination on the screen 2 Uniform darkness on the screen 3 Equally spaced white and dark bands 4 A few coloured bands and then uniform illumination

13 For what distance is ray optics a good approximation when the aperture is 4 mm wide and the wavelength is 500 nm 1 32 m 3 16 m 2 69 m 4 8 m

In a double slit experiment the two slits are 1 mn apart and the screen is placed 1 m away A monochromatic light of wavelength 500 nm i used What will be the width of each slit fc obtaining ten maxima of double slit within th central maxima of single slit pattern a 0 5 mm b 0 02 mm c 0 2 mm d 0 1 mm

by the thin convex lens is where length of convex lens is 10 cm and it is placed along y axis 1 10 10 cm 45 YA 2 10 20 cm

1 Light of wavelength 589 3 nm is incident normally on a slit of width 0 01 mm The angular width of the central diffraction maximum at a distance of 1 m from the slit is 1 0 68 2 0 34 3 2 05 4 6 75

A lens having focal length f and aperture of diameter d forms an image of intensity I Aperture d of diameter in central region of lens is covered 2 by a black paper Focal length of lens and intensity of image now will be respectively f 1 and 1 2 2 2 fand 3 3f 4 4 and 31

Interference pattern is observed at P due to superimposition of two rays coming out from a source S as shown in the figure The value of for which maxima is obtained at P is R is perfect reflecting surface S 2n 1 2n 3 1 2 l 2 3 1 1 3 l 2n 1 3x 4 2 3 4 l 2n 1 3 1 121 30 R 2014

In diffraction using single slit a slit of width a is illuminated by white light For red light 6500 A the first minima is obtained for 0 30 Then the value of a will be To cos 0 Z 1 3250 A 3 1 30 m 2 6 5 10 4 Cos 8 1 o 4 2 6 x 10 4 25 ottern on a single slit does not depend upon 0 45

Two monochromatic light beams of intensity 16 and 9 units are interfering The ratio of intensities of bright and dark parts of the resultant pattern is 1 16 9 3 4 3 2 7 1 4 49 1 2014

In double slit experiment what should be the width of each slit to obtain 10 maxima of the double slit pattern within the central maxima of single slit pattern with d 2 mm Pusa Road New Delhi 110005 Ph 011 47623456 Quer

arrangement the slits are separated by a distance equal to 100 times the wavelength of the light passing through the slits a What is the angular separation in radians between the central maximum and an adjacent maximum b What is the distance between these maxima on a screen 50 0 cm from the

39 Two polaroids are oriented with their transmission axes making angle of 30 with each other The fraction of incident unpolarised light transmitted is 1 37 3 3 36 2 62 5 4 36 5

5 A double slit arrangement produces interference fringes for sodium light 589 nm that are 0 20 apart What is the angular fringe separation if the entire arrangement is immersed in water n 1 33 one of the sli is twice the in from the oth approximate bright and interfere

23 Monochromatic electromagnetic radiation from a distant source passes through a slit The diffraction pattern is observed on a screen 2 50 m from the slit If the width of the central maximum is 6 00 mm what is the slit width if the wavelength is a 500 nm visible light b 50 m infrared radiation c 0 500 nm X rays

32 An achromatic prism is made by crown glass prism Ac 19 and flint glass prism AF 6 If n 1 5 and F then resultant deviation for red coloured ray will be n 1 66 a 1 04 c 0 96 b 5 d 13 5

The distance between two consecutive bright fringes in a biprism experiment using light of wavelength 6000 is 0 32 mm by how much will the distance change if light of wavelength 4800 is

ection D YDSE with glass slab Optical path 1 A flint glass and a crown glass are fitted on the two slits of a double slit apparatus The thickness of the strips is 0 40 mm and the separation between the slits is 0 12 cm The refractive index of flint glass and crown glass are 1 62 and 1 52 respectively for the light of wavelength 480 nm which is used in the experiment The interference is observed on a screen a distance one meter away a What would be the fringe width b At what distance from the geometrical centre will the nearest maximum be located

2 It is necessary to illuminate the bottom of a I well by reflected solar beam when the light is incident at an angle 40 to the vertical At what angle to the horizontal should a plane mirror be placed 1 65 2 70 3 75 4 80

20 At the first minimum adjacent to the centra maximum of a single slit diffraction pattern the phase difference between the Huygen s wavele from the edge of the slit and the wavelet from th mid point of the slit is 2100 1 radian T 3 radian TC 2 radian 4 4 radian A

2 You are given four sources of light each one providing a light of a single colour red blue green and yellow Suppose the angle of refraction for a beam of yellow light corresponding to a particular angle of incidence at the interface of two media is 90 Which of the following statements is correct if the source of yellow light is replaced with that of other lights without changing the angle of incidence a The beam of red light would undergo total internal reflection b The beam of red light would bend towards normal while it gets refracted through the second medium c The beam of blue light would undergo total internal reflection d The beam of green light would bend away from the normal as it gets refracted through the second medium

on A Cylindrical planer light beam incident normally on a medium Where refractive index is increasing radially across cross section beam will diverge just after refraction Reason Speed of light is lower in region of high refractive index 1 A 3 C 2 B 4 D

5 33 A double slit interference pattern is produced on a screen as shown in the figure using monochromatic light of wavelength 500 nm Point P is the location of the central bright fringe that is produced when light waves arrive in phase without any path difference A choice of three strips A B and C of transparent materials with different thicknesses and refractive indices is available as shown in the table These are placed over one or both of the slits singularly or in conjunction causing the interference pattern to be shifted across the screen from the original pattern In the column I how the strips have been placed is mentioned whereas in the column II order of the fringe at point P on the screen that will be producee due to the placement of the strip s is shown Correctly match both the column Slit 1 Sint 11 Column I P Screen Film Thickness in um Refractive Index A Only strip B is placed over slit 1 B Strip A is placed over slit I and strip C is placed over slit II C Strip A is placed over the slit I and strip B and strip C are placed over the slit II in conjunction D Strip A and strip C are placed over slit 1 in conjuction and strip B is placed over slit II A 5 1 5 Column II B 1 5 2 5 p First Bright q Fourth Dark r Fifth Dark s Central Bright C 0 25 2

2 Two plane mirrors A and B are aligned parallel to each other as shown in the figure A light ray is incident at an angle 30 at a point just inside one end of A The plane of incidence coincides with the plane of the figure The maximum number of times the ray undergoes reflections including the first one before it emerges out is 1 28 0 2m 2 30 2 3 m B 30 A 3 32 4 34

A star is emitting light at the wavelength of 5000 A Determine the limit of resolution of a telescope having an objective of diameter of 200 inch Ans 1 2x107 rad

9 A spaceship is moving with a velocity 108 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 2 4500 A 3 5500 A 4 6500 A