Wave Optics Questions and Answers

Two coherent sources are separated by a distance d 2X are placed at the centre of a large circular screen arranged symmetrically as shown R is radius of circular screen R d Light of wavelength is used in the experiment How many bright fringes will be observed on screen from A to B first quadrant Y axis S S 2186 B Circular screen 2 3 4 X axis

Anna looks at white light through a slit in a spectroscope and sees a rainbow of colors Which of these is the best explanation for why she sees many colors O The colors in the white light refract different amounts The frequency of the white light is changing when it passes through the slit The colors in the white light diffract different amounts The amplitude of the white light is changing when it passes through the slit

Two point monochromatic and coherent sources of light of wavelength are placed on the dotted line infront of an infinite screen The sources emit waves in phase with each other The distance between S and S is d while their distance from the screen is much larger than d assume equal intensity at O due to individual source S S THE N A if d is 32 at O minima will be observed 112 B if d is then intensity at O will be C if d is 32 O will be maxima 7A al tancity at will be 3 0 GROUP 23 of maximum intensity of maximum intensity

2 What is the critical angle for the light rays hitting cornea from the inside of the eye for them not being able to leave the eye assume the medium in the eye has refractive index 1 38 1 48 7 2 45 2 3 46 4 19 1

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 d A 3 C 6 d2d 3 B 5 D 4 10

let be the In a Young s double slit experiment fringe width and let I be the intensity at the central bright fringe At a distance x from the central bright fringe the intensity will be B 1 cos A Io cos C I cos B HF B D cos B

Two identical loudspeakers are placed on a line at distance 4 m and 6m from a microphone lying on the line joining them The output of each speaker at the microphone is 2 mW If the two speakers are connected in series and excited by the same oscillator and they vibrate in phase with each other the resultant output at the microphone will be frequency of oscillator 660 Hz and speed of sound 330 m s A zero B 2 mW C 4 mW D 8 mW

9 The first diffraction minimum due to a single slit diffraction is at angle 0 30 for a light of wavelenth 5000A The width of the slit is 1 5 x 10 5cm 2 1 x 10 cm 3 2 5 x 10 4cm 4 1 25 x 10 5cm 007 S 8

Figure shows the displacement time graph of a particle executing SHM with a time period T Four points 1 2 3 and 4 are marked on the graph where the displacement is half that of the amplitude A 2 0 A 2 A Ap 2 T a Identify the points of same displacement but with opposite direction of motion Find the time difference between them 2 b Identify the points where the particles move in the same direction Find the time difference between them T 4 Sol a Points 1 and 2 have same displacements x 4 2 with equal but opposite velocities Similarly points 3 and 4 have same displacements x A 2 with equal but opposite velocities The phase difference between 1 and 2 and 3 and 4 is t 3 Therefore the time difference is T 27

Red light 1 600 nm falls on a single slit an forms a diffraction pattern on a white marke board 1 50 meters away If the second dark band is located 4 5 cm from the central brigh fringe find the width of the slit in micrometers

The radius of the objective lens of a telescope is 5 cm and wavelength of light is 5000A The telescope is situated at a distance of 1 km from two objects The minimum distance between the two objects which can be resolved by the telescope is approximately 1 0 6 m 3 6 mm 8 2 6 m het to bon nirt A 08 4 6 cm

1 A transverse wave is travelling along a horizontal string The first picture shows the shape of the string at an instant of time This picture is superimposed on a coordinate system to help you make any necessary measurements The second picture is a graph of the vertical displacement of one point along the string as a function of time How far does this wave travel along the string in one second KA NAA 6 10 12 14 16 18 seconds centimeters A 0 3 cm B 3 0 cm C 9 0 cm D 27 cm

As shown mono energetic x rays with a wavelength of 0 35 nm are diffracted by a crystal The angle relative to normal incidence to the crystal is 8 0 The first diffraction maximum is observed when 0 77 What is the lattice spacing d O 0 12 nm 0 18 nm 1 6 nm 0 38 nm 0 78 nm d 0 36 nm

A beam of bright red light of wavelength 654 nm passes through a diffraction grating Enclosing the space beyond the grating is a large semicylindrical screen centered on the grating with its axis parallel to the slits in the grating Fifteen bright spots appear on the screen Find the minimum possible values for the slit separation in the diffraction grating

4 In Young s double slit experiment the wavelength of red light is 7800 and that of blue light is 5200 A The value of n for which nth bright band due to red light coincides with n 1 bright band due to blue light is a 1 c 3 6 2 d 4

3 Two polaroid sheets are placed one over the other with their axes inclined to each other at an angle If only 12 5 of the intensity of the light incident on the first sheet emerges out from the second sheet the value of is 0 1 30 2 60 3 45 4 90