Title 29. Wave Optics Hard.pdf ✅

1. If two light waves having same frequency have intensity ratio 4 : 1 and they interfere, the ratio of maximum to minimum intensity in the pattern will be (a) 9 : 1 (b) 3 : 1 (c) 25 : 9 (d) 16 : 25 2. In Young’s double slit experiment using sodium light ( = 5898Å), 92 fringes are seen. If given colour ( = 5461Å) is used, how many fringes will be seen (a) 62 (b) 67 (c) 85 (d) 99 3. Two beams of light having intensities I and 4I interfere to produce a fringe pattern on a screen. The phase difference between the beams is 2  at point A and  at point B. Then the difference between the resultant intensities at A and B is (a) 2I (b) 4I (c) 5I (d) 7I 4. If two waves represented by y 4 sint 1 = and       = + 3 2 3 sin  y t interfere at a point, the amplitude of the resulting wave will be about (a) 7 (b) 6 (c) 5 (d) 3. 5. Two waves being produced by two sources S1 and S2 . Both sources have zero phase difference and have wavelength . The destructive interference of both the waves will occur of point P if ( ) S1P − S2P has the value (a) 5 (b)  4 3 (c) 2 (d)  2 11 6. Two interfering wave (having intensities are 9I and 4I) path difference between them is 11 . The resultant intensity at this point will be (a) I (b) 9 I (c) 4 I (d) 25 I 7. In interference if 81 144 min max = I I then what will be the ratio of amplitudes of the interfering wave (a) 81 144 (b) 1 7 (c) 7 1 (d) 9 12 8. Two interfering waves having intensities x and y meets a point with time difference 3T/2. What will be the resultant intensity at that point (a) ( x + y) (b) ( x + y + xy ) (c) x + y + 2 xy (d) xy x y 2 + 9. In Young’s double-slit experiment, an interference pattern is obtained on a screen by a light of wavelength 6000 Å, coming from the coherent sources S1 and 2 S . At certain point P on the screen third dark fringe is formed. Then the path difference S1P − S2P in microns is (a) 0.75 (b) 1.5 (c) 3.0 (b) 4.5 10. In a Young’s double slit experiment, the slit separation is 1 mm and the screen is 1 m from the slit. For a monochromatic light of wavelength 500 nm, the distance of 3rd minima from the central maxima is (a) 0.50 mm (b) 1.25 mm (c) 1.50 mm (d) 1.75 mm 11. The two slits at a distance of 1 mm are illuminated by the light of wavelength 7 6.5 10 −  m. The interference fringes are observed on a screen placed at a distance of 1 m. The distance between third dark fringe and fifth bright fringe will be (a) 0.65 mm (b) 1.63 mm (c) 3.25 mm (d) 4.88 mm 12. The slits in a Young’s double slit experiment have equal widths and the source is placed symmetrically relative to the slits. The intensity at the central fringes is I0. If one of the slits is closed, the intensity at this point will be (a) I0 (b) I0 / 4 (c) I0 / 2 (d) 4 0 I 13. In double slit experiment, the angular width of the fringes is 0.20° for the sodium light ( = 5890 Å). In order to increase the angular width of the fringes by 10%, the necessary change in the wavelength is (a) Increase of 589 Å (b) Decrease of 589 Å (c) Increase of 6479 Å (d) Zero 14. In Young’s experiment, light of wavelength 4000 Å is used, and fringes are formed at 2 metre distance and has a fringe width of 0.6 mm. If whole of the experiment is performed in a liquid of refractive index 1.5, then width of fringe will be (a) 0.2 mm (b) 0.3 mm (c) 0.4 mm (d) 1.2 mm 15. Two identical sources emitted waves which produces intensity of k unit at a point on screen where path difference is . What will be intensity at a point on screen at which path difference is /4 (a) 4 k (b) 2 k (c) k (d) Zero 16. A thin mica sheet of thickness 6 2 10 −  m and refractive index ( = 1.5) is introduced in the path of the first wave. The wavelength of the wave used is 5000Å. The central bright maximum will shift (a) 2 fringes upward (b) 2 fringes downward (c) 10 fringes upward (d) None of these 17. In a YDSE fringes are observed by using light of wavelength 4800 Å, if a glass plate ( = 1.5) is introduced in the path of one of the wave and another plates is introduced in the path of the ( = 1.8) other wave. The central fringe takes the position of fifth bright fringe. The thickness of plate will be (a) 8 micron (b) 80 micron (c) 0.8 micron (d) None of these