Wave Optics Questions and Answers

16 In the given circuit current flow through resistance of 5 2 is 20 VT 1 15 A 3 5 A 22 59 5 V 2 10 A 4 Zero 192

You find a pair of eyeglasses and discover that each lens is able to focus the sun s rays to spot What type of vision problem does the owner of the glasses have A B Farsighted C Astigmatism D No vision problem these must be sunglasses Nearsighted

Light incident on a surface separating two media is partly reflected and partly refracted as shown in the figure Then 1212 1 sini 3 sini Sausa lla SPORD 90 H 21 22 ani 1 H 4 sini H2

1 A rod of length 10 cm lies along the principal axis of a concave mirror of focal length 10 cm in su way that the end closer to the pole is 20 cm away from it Calculate the length of the image 15 2 A small candle 2 5 cm in size is placed at 27 cm in front of a concave mirror of radius of curv 36 cm At what distance from the mirror should a screen be placed in order to obtain a sharp in Describe the nature and size of the image 54 cm real inverted magnified t

Select the correct statement 1 Interference is necessary for diffraction in YDSE 2 Diffraction is necessary for interference in YDSE 3 Young s double slit experiment is diffraction experiment 4 None of these

source of light Cylindrica Why are multiple colours observed over a thin film of oil floating on water Explain with the help of a diagram

12 Two tuning forks vibrating at 340 Hz each move relative to a stationary observer one away from the observer and the other towards the observer with the same speed along the same line joining the two forks and observer The observer hears beats of frequency 3 Hz The speed of the tuning forks is A 1 5 m s B 2 5 m s C 3 5 m s D 4 5 m s

Illustration 28 A lens having focal length 30 cm is cut along a plane parallel to the principal axis of the lens at a distance 5 mm above optical centre A and upper part of lens is shifted by 5 mm from the x axis as shown in the figure A point object is placed on the principal axis of the mirror at origin O 0 0 Find the number of images formed just after the reflection from the mirror and write their co ordinates 0 0 90cm f 30 cm A A mm 5 mm 30cm Megacosm Cognitions Pvt Ltd 57 Kalu Saral Sarvapriya Vihar New Delhi 110017 Email enquiry megacosmco

A young double slit apparatus is immersed in liquid of refractive index 4 3 as shown in figure Slit s and s is covered with thin glass of equal width having refractive index 5 3 and u respectively then A central maxima will be at point o when 4 3 B central maxima will be at point o when 5 3 H C central maxima will be below point o when 5 3 D Central maxima will be above point when 5 3 air D d kinetic er

It is found that when waves from two identical coherent sources superpose at a certain point the resultant intensity is equal to intensity of one wave only This means that the phase different between the two waves at that point is

The sun makes 0 5 angle on earth surface Its image is made by convex lens of 50 cm focal length The diameter of the image will be CPMT 2003 a 5 mm c 7 mm b 4 36 mm d None of these

Find the speed of light in diamond if its refractive index is 2 5 x Speed of light in vacuum 3 108 m s Ans

In YDSE the distance between two coherent sources is 0 2 mm and interference pattern is observed on the screen 80 cm from the sources If the wavelength of light used is 6000 the distance of second bright fringe from the first dark on the same side is 2 4 8 10 m 4 1 2 mm 1 2 4 mm 3 3 6 x 10 3 m

Problem 24 If the path difference produced due to interference of light coming out of two slits for yellow colour of light at a point on the screen be 32 2 what will be the colour of the fringe at the point Give reason also

In an YDSE the fringes are formed at a distance of 1 m from double slits of separation 0 12 mm Calculate the wave length of light used its distance of 3rd bright band from the centre of screen is 1 5 cm 1 6000 3 4000 1 2 5000 00 Guill 4 8000 8

23 In the Young s arrangement screen starts moving towards right with constant speed v Initial distance between screen and plane of slits is x At t 0 1st order maxima is lying at point A After how much time first order minima lies at point A 10 1 3 X 2v X 31 Source X 2 A Screen t 0 4 V

The maximum number of possible interference maxima obtained on screen for slit seperation equal to twice the wavelength in Young s double slit experiment is 1 infinite 2 Five 3 Three 4 Zero

The equation of progressive wave is y 0 09 sin87 t x 20 after reflection of this wave from rigid end the amplitude of reflected wave becomes 2 3 of initial then i Find the equation of reflected wave ii Find the displacement of that particle which is situated at x 0 in reflected wave 14

3 1 18 In single slit diffraction pattern if intensity of centra maxima is then intensity of first secondar maxima is 1 4 5 of l 2 6 5 of lo 3 10 of

34 A beam of light consisting of two wavelengths 6500 and 5200 is used to obtain interference fringes in a Young s double slit experiment a Find the distance of the third bright fringe on the screen from the central maxima for the wavelength 6500 b What is the least distance from the central maxima where the bright fringes due to both the wavelength coincide The distance between the slits is 2 mm and the distance between the plane of the slits and screen

Magnification A positive What of virtual image is always B negative C greater than 1 D less

A wave of frequency 100 Hz travels along a string towards its fixed end When this wave travels back after reflection a node is formed at a distance of 10 cm from the fixed end The speed of the wave incident and reflected is 1 20 m s 2 40 m s 3 5 m s 4 10 m s

A short linear object of length b lies along the axis of concave mirror of focal length f at a distance u from pole of mirror The size of image is b UF f 1 b 3 b 1 f 2 f u f 4 1 u f f 2 b 2 4 b 7 u f

1 4 is used to cover one slit of Young s double slit experiment being performed using monochromatic beam of light of wavelength 6000 A If at the central point is now found the fifth bright fringe the thickness of the mica sheet is A 4 2 micron C 7 5 micron B 6 0 micron D 8 4 micron

In young s double slit experiment Assume intensity of each source is lo and K is equal to difference of maximum and minimum intensity Now intensity of one source is made and K is K 2 again difference of maximum and minimum intensity Then 3 A 4 C 4 B 3 D 2 K2

Which of the following functions represent a travelling wave a x vt b n x vt c a x d 1 x vt

5 A poloroid sheet and an analyzer are placed such that their transmission axes are parallel The analyzer is then rotated by 22 5 What is the intensity of the transmitted light as a fraction of intensity of light incident on analyser 2 0 68 4 0 87 1 0 45 3 0 41

Example 10 4 What is the effect on the interference fringes in a Young s double slit experiment due to each of the following operations a the screen is moved away from the plane of the slits b the monochromatic source is replaced by another monochromatic source of shorter wavelength c the separation between the two slits is increased d the source slit is moved closer to the double slit plane e the width of the source slit is increased f the monochromatic source is replaced by a source of white light Tot able to understand d part o mentioned in d below d Et s be the size of the source and S its distance from the plane of the two slits For interference fringes to be seen the condition s S A d should be satisfied otherwise interference patterns produced by different parts of the source overlap and no fringes are seen Thus as S decreases i e the source slit is brought closer the interference pattern gets less and less sharp and when the source is brought too close for this condition to be valid the fringes disappear Till this happens the fringe senaration remains fixed es that mean JIGSAW M

7 In a Fresnel biprism experiment the two positions of lens give separation between the slits as 16 cm and 9 cm respectively What is the actual distance of separation 1 13 cm 2 14 cm 3 12 5 cm 4 12 cm

A circular disc of diameter d lies horizontally inside a metallic hemisphere bowl of radius 12 5 cm The disc is just visible to an eye looking over the edge The bowl is now filled with an liquid of refractive index 4 3 Now the whole of the disc is just visible to the eye in the same position d in cm will be

The mathematical forms for three sinusoidal travelling waves are given by P Wave 1 y x t 2cm sin 3x 6t Wave 2 y x t 3cm sin 4x 12t Wave 3 y x t 4cm sin 5x 11t where x is in meters and t is in seconds Of these waves 25 1 wave 1 has the greatest wave speed and the greatest maximum transverse string speed 2 wave 2 has the greatest wave speed and wave 1 has the greatest maximum transverse string speed 3 wave 3 has the greatest wave speed and the greatest maximum transverse string speed A 4 wave 2 has the greatest wave speed and wave 3 has the greatest maximum transverse string

Aakash Rank Booster Test Series for NEET 2020 In the figure shown if a parallel beam of white light is incident on the plane of the slits then the distance of the nearest white spot on the screen from O is d A Find the value of A Assume d D 1 3 d2d 3 D 2 5 O

A wave front AB passing through a system C as DE The system C could be emerges A D F B A a slit C a prism C E B a biprism D a glass slab

4 In an isotropic medium the secondary wavelets centred on every point of a given wavefront are all a Spherical b c Oval d of arbitrary shape Cylindrical

A sound of intensity 27 lo is produced at the end A It travels down to the point B along three different paths I II and III as shown in the figure Path II is semi circular At B no sound is heard a Find the maximum possible wavelength of sound b Find the minimum value of x for above wavelength c Find the equations of the three waves arriving at B Assume that sound energy is equally distributed among the three paths The path length III is more than that of II The amplitude of wave corresponding to intensity lo is A The wave velocity is v A 1 0m B

A ray of light is incident at an angle i from denser to rare medium The reflected and the refracted rays are mutually perpendicular The angle of reflection and the angle o refraction are respectively and then the critical angle wil be CBSE PMT 1996 Pb PET 2002 AIIMS 2010 a sin sin r b sin tan r c sin tan i d sin sin i

A long solenoid of diameter 0 1 m has 2 x 104 turns per meter At the centre of the solenoid a 100 turn coil of radius 0 01 m is placed with its axis coinciding with the solenoid axis The current in the solenoid is decreased at a constant rate from 2 A to 2 A in 0 05 sec Find the emf induced in the coil Also find the total charge flowing through the coil during the time when the resistance of the coil is 10 Q

38 A beam of unpolarised light is incident on a tourmaline crystal C The intensity of the emergent light is I and it is incident on another tourmaline crystal C It is found that no light emerges from C If now C is rotated through 45 towards C the intensity of the light emerging from C is In In 310

In Young double slit experiment how many minimas can be obtained on a screen if wavelength of light used is 2000 and slit width is 0 0008 mm 1 6 10 2 7 4 9

7 In Young s double slit experiment shown in figur th S1 and S2 are coherent sources and S is screen having a hole at a point 1 0mm away fro the central line White light 400 to 700nm sent through the slits Which waveleng passing through the hole has strong intensit Tc 0 5mm 400 nm 500 pm S S 50cm Centre of screen hole S Screen 1 0mm b 700 nm d 667pm

6 Light waves of intensities and 9 interfere to produce a fringe pattern on a screen The phase 3 difference between the wave at a point P is 2 and 2 at other point Q Then the ratio of intensities at P and Q is ripil 1 8 5 2 5 8 3 1 4 4 1

Two coherent sources of wavelength 6 2 x 10 7m produce interference The path difference corresponding to dark fringe between third and fourth maxima will be 6 2x 10 7 7 2 17 x 10 m a 4 17 x 10 m 10 6 jo c 6 17 x 10 m d 8 17 x 10 m 2

s answer out of which only ONE OR MORE THAN ONE is are correct Two parallel beams of light P and Q separation d containing radiation of wavelength 4000 and 5000 are incident normally on a prism as shown in figure The refractive index of the prism as a function of wavelength is b given by u 2 1 20 where 2 in and b is a 2 positive constant The value of b is such that the condition for total internal reflection of the face AC is satisfied for one wavelength and not for the other then sin 80 3 0 9856 A The value of b 8 x 10 15 m B Deviation of beam transmitted through face AC is 27 2 C The value of b 4x10 5 m 2 D Deviation of beam transmitted through face AC is 38 7 P A B A sin 0 8

In Fraunhoffer diffraction pattern angular widt of central maximum is a sin c sin 2 d d b 2 sin d sin 4 2 2d

Two speakers are placed as shown in Fig S 1 A B X HS D Mark out the correct statement s 1 If a person is moving along AB he will hear the sound as loud faint loud and so 2 If a person moves along CD he will hear loud faint loud and so on 3 If a person moves along AB he will hear uniform intense sound If a person moves along CD he will hear uniform intense sound

Two metal spheres have radii r and 2r and they emit thermal radiation with maximum intensities at wavelengths and 22 respectively The respective ratio of the radiant energy emitted by them per second will be 3 27 1 1 4 1 3 16 1 Oor 1 2 1 4 4 8 1

4 96 In Fraunhoffer diffraction the centre of diffraction image is Vi 1 always bright 2 always dark 3 sometimes bright and sometimes dark 102 4 bright for large wavelength and dark for low wavelength

A lens is made of flint glass refractive index 1 5 When the lens is immersed in a liquid of refractive index 1 25 the focal length 1 Increases to a factor of 1 25 2 Increases to a factor of 2 5 3 Increases to a factor of 1 2 4 Decreases to a factor of 1 2

1 A fish in water refractive index n looks at a bird vertically above in the air If y is the height of the bird and x is the depth of the fish from the surface then the distance of the bird as estimated by the fish is a x x 1 1 n c x y 1 n y x 1 1 b d x ny

A telescope has an objective lens of 10 cm diameter and is situated at a distance of one kilometre from two objects The minimum distance between these two objects which can be resolved by the telescope when the mean wavelength of light is 5000 is of the order of CBSE AIPMT 2004 d 5 cm c 5 mm