Title 3.WAVE OPTICS FINAL.pmd.pdf ✅

NISHITH Multimedia India (Pvt.) Ltd., 89 JEE MAINS - CW - VOL - I JEE ADVANCED - VOL - V WAVE OPTICS NISHITH Multimedia India (Pvt.) Ltd., LEVEL - V SINGLE CORRECTANSWER TYPE 1. The YDSE apparatus is as shown in figure below. The condition for point ‘P’ to be a dark fringe is [ = wavelength of light used] 1 S S 2 S 1 l 2 l 3 l 4 l P Screen (A) l l l l n 1 3 2 4         (B) l l l l n 1 2 3 4         (C)  1 3 2 4    2 1 2 l l l l n       (D)  1 2 3 4    2 1 2 l l l l n       2. Intensity observed in an interference pattern 2 0 I I  sin  . At 30o   , intensity I  5 0.002. The percentage error in angle if 2 0 I w m  20 / is (A) 2 4 3 10 %  (B) 4 2 10 %    (C) 4 3 2 10 %    (D) 2 3 10 %  3. A screen is at a distance D=80cm from a diaphragm having two narrow slits 1 S and 2 S which are d mm  2 apart. Slit 1 S is covered by a transparent sheet of thickness 1 t m  2.5 and slit 2 S is covered by another sheet of thickness 2 t m 1.25 as shown in figure. Both sheets are made of same material having refractive index  1.4. Water is filled in the space between the diaphragm and screen. A monochromatic light beam of wavelength   5000Å is incident normally on the diaphragm. Assuming intensity of beam to be uniform calcualte ratio of intensity at C to the maximum intensity of interference patern obtained on the screen? 4 3       1 t 2 t 1 S S2 C (A) 3 4 (B) 2 3 (C) 8 9 (D) 5 7 WAVE OPTICS
90 NISHITH Multimedia India (Pvt.) Ltd., JEE ADVANCED - VOL - V NISHITH Multimedia India (Pvt.) Ltd., WAVE OPTICS 4. In the given figure, S is a monochromatic point source emitting light of wavelength   500nm . A thin lens of circular shape and focal length 0.1m is cut into two identical halves L1 and L2 by a plane passing through daimeter. The two halves are placed symmetrically placed about the central axis SO with gap of 0.5mm. The distance along the axis the from S to L1 and L2 is 0.15m, while that from L1 and L2 to ‘O’ is 1.3m. The screen at O is normal to SO. If the third maxima occurs at point A on the screen find the disntance OA? 0.15m 1.3m 0.5mm A S O L1 L2     (A) 1 mm (B) 2 mm (C) 1.5 mm (D) 2.5 mm 5. In a standard YDSE the region between screen and slits is immersed in a liquid whose refractvie index varies with time as 5 2 4 l T    until it reaches a steady state value of 5 4 . A glass plate of thickness 36m and refractive index 3 2 is introduced in front of one of the slits. Find the velocity of central maximuma when it is at ‘O’?(take d=2mm and D=1m) (A) 3 1 2 10 ms    (B) 3 1 3 10 ms    (C) 3 1 4 10 ms    (D) 3 1 5 10 ms    6. In a double slit experiment instead of taking slits of equal widths, one slit is made twice as wide as the other, then in the interference pattern: (2000; 2M) (A) the intensities of both the maxima and the minima increases (B) the intensity of the maxima increases and the minima has zero intensity (C) the intensity of maxima decreases and that of minima increases (D) the intensity of maxima decreases and the minima has zero intensity 7. 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 resultant intensities at A and B is: (2001; 2M) (A) 2 I (B) 4 I (C) 5 I (D) 7 I 8. In a Young’s double slit experiment, 12 fringes are observed to be formed in a certain segment of the screen when light of wavelength 600 nm is used. If the wavelength of light is changed to 400 nm, number of fringes observed in the same segment of the screen is given by : (2001; 2M) (A) 12 (B) 18 (C) 24 (D) 30 9. In the ideal double-slit experiment, when a glass-plate (refractive index 1.5) of thickness t is introduced in the path of one of the interfering beams (wavelength  ), the intensity at the position where the central maximum occurred previously remains unchanged. The minimum thickness of the glass-plate is : (2002; 2M) (A) 2 (B) 2 3  (C) 3  (D)
NISHITH Multimedia India (Pvt.) Ltd., 91 JEE MAINS - CW - VOL - I JEE ADVANCED - VOL - V WAVE OPTICS NISHITH Multimedia India (Pvt.) Ltd., 10. In an interference arrangement similar to Young’s double-slit experiment, the slits S1 and S2 are illuminted with coherent microwave sources, each of frequency 106 Hz. The sources are synchronized to have zero phase difference. The slits are separated by a distance d = 150.0 m. The intensity I (q) is measured as a function of q, where q is defined as shown. If I 0 is the maximum intensity, then I(q) for 0 < q < 90° is given by : (1995; 42) (A) I(q) = I 0 /2 for q = 0 45 (B) I(q) = I 0 /4 for q = 90° (C) I(q) = I 0 for q = 0° (D) I(q) is constant for all values of q 11. In a Young’s double slit experiment, the separation between the two slits is d and the wavelength of the light is  . The intensity of light falling on slit-1 is four times the intensity of light falling on slit 2. Choose the correct choice(s), (A) if d =  , the screen will contain only one maximum (B) if 2 d     , at least one more maximum (besides the central maximum) will be observed on the screen (C) if the intensity of light falling on slit 1 is reduced so that it becomes equal to that of slit 2, the intensities of the observed dark and bright fringes will increase (D) if the intensity of light falling on slit 2 is reduced so that it becomes equal to that of slit 1, the intensities of the observed dark and bright fringes will increase. 12. In a YDSE be-chromatic light of wavelengths 400 nm and 560 nm are used. The distance between the slits is 0.1 mm and the distance between the plane of the slits and the screen is 1 m. The minimum distance between two successive regions of complete darkness is : (2004; 2M) (A) 4 mm (B) 5.6 mm (C) 14 mm (D) 28 mm 13. In Young’s double slit experiment intensity at a point is 1 4       of the maximum intensity. Angular position of this point is:(2005; 2M) (A) sin–1 d        (B) sin–1 2d        (C) sin–1 3d        (D) sin–1 4d        14. In the Young’s double slit experiment using a monoclromatic light of wavelenght  , the path difference (in terms of an integer n) corresponding to any point having half the peak intensity is (A) 2 1 2 n   (B)2 1 4 n   (C)2 1 8 n   (D)2 1 16 n   MULTIPLE ANSWER QUESTIONS 15. White light is used to illuminate the two slits in young’s double slit experiment. The seperation between the slits is b and the screen is at a distnace d(d>>>b) from the slits. At a point on the screen directly in front of one of the slits, certain wavelength are missing. Some of these missing wavelengths are (A) 2 b d   (B) 2 2b d   (C) 2 3 b d   (D) 2 2 3 b d   16. Two point monochromatic and coherent sources of light of wavelength  are each placed as shown in the figure below. The initial phase difference between the sources is zero.(Assume D>>>d). Select the correct statement(s). S1 S2 d   D O Screen
92 NISHITH Multimedia India (Pvt.) Ltd., JEE ADVANCED - VOL - V NISHITH Multimedia India (Pvt.) Ltd., WAVE OPTICS (A) If 7 2 d   , the point ‘O’ will be minima. (B) If d   , only one maxima canbe observed on screen (C) If d  4.8 ,then a total 10 minimas would be there on screen. (D) If 5 2 d   , then Intensity at ‘O’ would be minimum. 17. The minimum value of ‘d’ so that there is a dark fringe at ‘O’ is min d . For the value of min d the distance at which the next bright fringe is formed is x. Then A P O O ' B x D D d (A) d D min   (B) min 2 D d   (C) min 2 d x  (D) min x d  COMPREHENSION TYPE Comprehension-I: In the arrangement shown in figure, slits S3 and S4 are having a variable separation Z. Point ‘O’ on the screen is at the common perpendicular bisector of S1 S2 and S3 S4 . (Assume D>>>d). D D O A O ' 1 S 2 S 3 S 4 S Z d 18. When 2 D Z d   the intensity meausred at ‘O’ is 0 I . The intensity at ‘O’ when 2 D Z d   is (A) 0 I (B) 0 2I (C) 0 3I (D) 0 4I 19. The minimum value of Z for which the intensity at ‘O’ is zero is (A) 3 2 D d  (B) 2 D d  (C) 3 D d  (D) D d  20. If a hole is made at O' on AO O' and the slit 4 S is closed then the ratio of the maximum to the minimum observed on screen at ‘O’ if 3 O S' is equal to 4 D d  is (A) 1 (B) Infinity (C) 34 (D) 4 Comprehension-II: A monochromatic beam of light falls on Young’s double slit experiment apparatus as shown in figure. A thin sheet of glass is inserted in front of lower slit 2 S (   600nm is wavelength of source) O d S1 S2 d D   t  21. The central bright fringe can be obtained (A) At ‘O’ (B) At ‘O’ or below ‘O’ (C) at ‘O’ or above ‘O’ (D) Any where on the screen 22. If central bright fringe is obtained onscreen at ‘O’ then (A)     1 sin t d (B)     1 cos t d (C)   t d   (D)  1 sin  t d    