Wave Optics Questions and Answers

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