Wave Optics Questions and Answers

Monochromatic light is passed through double slit and interference pattern is observed on screen 2 5 m away The separation between slits is 0 5 mm The first bright fringe is 3 5 mm away from central fringe The wavelength of light used is 600 nm 500 nm 650 nm 700 nm

In Young s double slit experiment if the source of light changes from orange to blue then 1 the central bright fringe will become a dark fringe mathongo 2 the distance between consecutive fringes will decrease mathong 3 the distance between consecutive fringes will increase 4 the intensity of the minima will increase athongo mathongs mathongs matho mathongo mathor mathongo mathongos

15 In Young s double slit experiment using a source of light of wavelength 5000 the fringe width is 0 6 mm If the distance between the screen and the slit is reduced to half then what should be the wavelength of light used to get fringes 0 4 mm wide 3 33 x 10 6 cm Pro 6 66 x 10 6 cm 33 3 x 10 6 cm 66 6 x 10 6 cm B D

The intensity at the maximum in a Young s double slit experiment is Io Distance between two slits is d 5A where A is the wavelength of light used in the experiment What will be the intensity in front of one of the slits on the screen placed at a distance D 10d

coherent Two closely located monochromatic sources create a fixed interference pattern on a screen The frequency of one of the sources is then decreased What will happen to the interference pattern as a result The pattern will completely disappear The fringe spacing will increase X The fringes will shift up or down but the spacing will remain constant The fringe spacing will decrease

In an interference of light derived from two sl apertures if at some point on the screen yellow light has a path difference of 32 2 then the fringe at that point will be 1 yellow in colour 3 dark 2 white in colour 4 bright WOOO

18 In a Young s double slit experiment the intensity at the central maximum is The intensity at a distance 3 4 from the central maximum is is fringe width 1 3 2 4 lo 2 lo

A sound wave given by Ap Apo sinw t r v is produced at z 0 and the reflected wat from other end of the closed tube produces standing wave What is the equation of the stand wave produced A Apr 2Apo cos wt sin Apr 2Apo sin ut cos C B Apr Apo sin ut cos D Apr Apo coswt sin

A glass sheet 1 40 m thick is suspended in air In reflected light there are gaps in the visible spectrum at 529 nm and 605 00 nm Calculate the minimum value of the index of refraction n of the glass sheet that produces this effect

A beam of light of wavelength 600 nm from a distance source falls on a single slit 1 mm wide and a resulting diffraction pattern is observed on a screen 2 m away The distance between the first dark fringes on either side of central bright fringe is A 1 2cm B 1 2mm C 2 4cm

A short pulse of white light is incident from air to a glass slab at normal incidence After travelling through the slab the first colour to emerge is 1 Blue 2 Green 3 Violet 4 Red

A linear aperture whose width is 0 02 cm is placed immediately in front of a lens of focal length 60 cm The aperture is illuminated normally by a parallel beam of wavelength 5 x 105 cm The distance of the first dark band of the diffraction pattern from the centre of the screen is a 0 10 cm b 0 25 cm c 0 20 cm d 0 15 cm

5 In a single slit diffraction pattern if the light source is used of less wavelength than previous one then width of the central fringe will be 1 less 2 increased 3 Unchanged 4 None

A single slit of width 0 20 mm is illuminated with the light of wavelength 500 nm The screen is placed 80 cm from the slit The width of the central bright fringe will be 0 1 mm 0 2 mm O 4mm O 5mm

Young s double slit experiment is performed in air an then performed in water The fringe width O will remain same O Will decrease O Will increase O Will be infinite H AMER

In ultrasonic interferometer the distance between two positions of reflector at which maximum current is found is 2 5 mm The velocity of the sound sound in air is 440 m s The frequency of the ultrasound used is 88 kHz 176 kHz 1 10 MHz 2 MHZ

View In English If the first minima in a young s slit experiment occurs directly in front of one of the slits then the wavelength of the radiation used is assume d D 1 2 3 4 6D Correct Answer 1 Status unattempted

5 A ray of light falls on a transparent glass slab of refractive index 1 62 If the reflected ray and refracted ray are mutually perpendicular the angle of incidence is 1 tan 1 62 3 tan 1 33 2 tan 4 tan 1 62 1 33

In a young s double slit experiment the slits are illuminated by monochromatic light The entire set up is immersed in pure water Which of the following act cannot restore the original fringe width 1 bringing the slits close together 2 moving the screen away from the slit plane 3 replacing the incident light by that of a longer wavelength 4 introducing a thin transparent slab in front of one of the slits

and diffraction 1 In interference distance between bright and dark is same but in diffraction width of central maxima is double of other maxima 2 Interference pattern is superposition of two waves originating from two narrow slits diffraction pattern is superposition of a continuous family of waves originating from each point on a single slit 3 For a single slit of width a the first null of the interference pattern occurs at an angle ment is wrong about interference 3 2 a maxima for two narrow slits separated by a distance a Inton of At the same angle of a we get a

2 An equilateral prism of mass m resets on a rough horizontal surface with coefficient of friction A horizontal force F is applied on the prism as shown in the figure If the coefficient of friction is sufficiently high so that the prism does not slide before toppling the minimum force required to topple the prism is F 1 mg 3 2 mg 4 3 a mg 3 umg 4 4

In same phase If AB is incident wavefront Then refracted 4 wavefront just after transmission is D 1 A B 2 A B Biconvex lens 3 A B 4 B A Two source are said to be coherent when 5

In a single slit diffraction experiment the wid of the slit is made double the original widt How does this affect the intensity of the centr diffraction band large 1 becomes double 2 becomes half 3 becomes one fourth 4 becomes 4 times When a tiny circular obstacle i path of ligh

prediced In single slit diffraction if we use red light in place of blue light then 1 fringe pattern will spread 2 fringe pattern becomes narrow 3 No change 4 Nothing can be prediced Diffraction is possible in waves 1 Sound waves 3 Matter waves Colour appear in CD i 2 Water waves 4 All type

32 2 What happens when two separate light sourc illuminate a wall 1 Uniform illumination 2 Interference fringes 3 Dark appear 4 Four times intensity of point

An ordinary light is pass from a polaroid 41 sheet P Then after P another polaroid sheet P is placed then Intensity of light after P will be 2 1 remain same 2 half 3 Zero 4 Charge from zero to half of intensity of igad light unn

In young s double slit experiment the central bright fringe can be identified 1 as it has greater intensity than the other bright fringe 2 as it is wider than the other bright fringes 3 as it is narrower than the other bright fringe 4 by using white light instead of

c The limits of visible spectrum are approximately 400nm to 700nm Find the angular width of the first order visible spectrum produced by a plane grating having 1500 lines per inch when light 2 Marks is incident normally on the grating

A polaroid is placed in the path of an incoming unpolarised light of intensity lo The intensity of light passing through polaroid after polarisation would be lo 10 2 O 10 4

Two coherent monochromatic light beams of intensities and 4 are superimposed The maximum and minimum possible intensities of the resulting beam are 51 1 51 3 91 1

Some currency notes change their colour as you see them This is due to A Diffraction B C Polarization Interference

Young s double slit experiment is performed in air and then performed in water The fringe width Will remain same Will decrease Will increase hr miny Will be infinite

A A wedge free to move of mass M has one face making an angle a with horizontal and is resting on a smooth rigid floor A particle of mass m hits the inclined face of the wedge with a horizontal velocity vo It is observed that the particle rebounds in vertical direction after impact Neglect friction between particle and the wedge take M 2m vo 10m s tana 2 g 10m s a M

99 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 O A 1 52 O 11 1 38 O c 1 40 O 0 1 62 30 bround to have full cireu view of the roomurrou

1 When a thin transparent plate of refractive index 1 5 is introduced in one of the interfering beams a shift of 20 fringes is observed If it is replaced by another thin plate of half the thickness and of refractive index 1 7 the number of fringes that will be 1 23 3 28 4 7 undergo shift EN PAR

A ray of light is incident at an angle a at the boundary separating two transparent media The light is transmitted However if the angle of incidence is increased very slightly the ray gets refracted into the incident medium The difference between the angles by which the incident light is deviated in the first case and that in the second case is A 2 B 90 C 180

13 discharging graph In YDSE D 10 m d 1 mm and fringe width of interference pattern is 0 6 nm evaluate in nm 600 0 6 x 10 10xx 10 3 0 6 107 m 600 10 m 600 nm IMG 324005 ID i then INDIA

Two identical narrow slits S and S2 A very small completely absorbing strip is placed at distance y from the point C C is the point on the screen equidistant from S and S2 Assume d D where d and D have usual meanings When S2 is covered with a thin film of thickness t and refractive index of then shift in central to maximum is P A td 1 D tD 1 towards S2 towards S2 B td D towards S tD 1 towards S

b Monochromatic light passes through the double slit and causes interference Find the wavelength of the light source when the spacing of the slits is 1 2 mm the distance between the slits and the screen is 5 m and the spacing between the interference patterns is 2 mm

a The young s experiment was conducted using a green light source with a wavelength of 550 nm When the distance between the slit and the screen is 1m and the distance between the two slits is 15 m how far would the third bright pattern be from the centerline

Interference fringes were produced in YDSE using light of wavelength 5000 When a film of transparent material with 2 5 x 10 3 cm thick was placed over one of the slit opening the fringe pattern shifted by distance equal to 20 fringe width The refractive index of film mater O 1 2 O 1 3 O 1 4 O 1 5

A double slit apparatus is set up and green light is used to form the interference pattern The green light is then replaced by red light Which of the following changes may allow the spacing of the bright bands on the screen to remain unaffected by the change of light color Given that the distance between the slits is d and that between the plane of the slits and the screen is D Increase D Decreased W Both None

ook now to pro 6000 A songso he soon rhod Sp s n Dojo6 3x10 cm od Ke as odos os as bos bud sood Spode Sro 20 54 36ujo 5535 rdo c n58 ov to sogg 555 Xocoso 74 107 Options 1 1 25 2 1 33 3 1 4

DSE setup the pio prase un 9 both waves at point on the screen again the angular position 0 of point P on the screen is shown below Choose the INCORRECT statement 4 n 2 Answer A B C Your Attempt 8 Correct answer The separation between slits is 2 There are 4 minimas on the screen The first maxima above the centre is at 4 Rate this questic

Five identical polaroids are placed coaxially with 45 angular separation from adjacent one as shown in figure lo Intensity of unpolarised light The intensity of light emerging out of 5th polaroid is Only one correct answer A B 5 C To 3 2 1

White light containing wavelengths from 410 nm to 750 nm falls on a grating with 7700 slits cm T Part A How wide is the first order spectrum on a screen 3 90 m away Express your answer to three significant figures and include the appropriate units 0 HA Value SIMO

In Young s double slit experiment the interference pattern is found to have an intensity ratio between bright and dark fringes as 9 What is ratio of amplitudes of interfering coherent waves 2 1 Imancon 9 ICI Te IDI HI 3 F 3 351 352 51 51 I F 51 5 SI 51 2 2 IXA

a Both sides of a uniform film that has index of refrac tion n and thickness d are in contact with air For normal incidence of light an intensity minimum is observed in the reflected light at and an intensity maximum is observed at A where A A Assuming that no intensity minima are observed between and 2 show that the integer m in Equations 37 16 and 37 17 is given by m A 2 A A b Determine the thickness of the film assuming n 1 40 A 500 nm and A 370 nm

Many cells are transparent and colorless Structures of great interest in biology and medicine can be practically invisible to ordinary microscopy An interference microscope reveals a difference in index of refraction as a shift in inter ference fringes to indicate the size and shape of cell structures The idea is exemplified in the following problem An air wedge is formed between two glass plates in contact along one edge and slightly separated at the oppo site edge When the plates are illuminated with monochro matic light from above the reflected light has 85 dark fringes Calculate the number of dark fringes that appear if water n 1 33 replaces the air between the plates

A coherent parallel beam of light of wavelength 5000 is incident normally on the plane of slits The slit S is covered with a slab of refractive index 1 5 and thickness t 4 105m as shown The separation between the slits is d 1 mm and the separation between the plane of slits and screen is D 1m Then the position of the central maxima formed on the screen is A 1 cm above point O B 2 cm above point O C 1 cm below point O D 2 cm below point O Hs 1 5 S Lt 4 x 10 m S D 1m scre