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10. WAVE OPTICS NEET PREPARATION (MEDIUM PHYSICS PAPER) Date: March 12, 2025 Dura on: 1:00:00 Total Marks: 180 INSTRUCTIONS INSTRUCTIONS PHYSICS 1. Assertion : Distance between position of bright and dark fringe remain same in Young's double slit experi‐ ment. Reason : Fringe width, (1) Both Assertion and Reason are cor- rect and Reason is the correct explana- tion of the Assertion. (2) Both Assertion and Reason are cor- rect but Reason is not the correct explana- tion of the Assertion. (3) Assertion is cor- rect but Reason is incorrect. (4) Both Assertion and Reason are incorrect. 2. Assertion : The maximum intensity in interference pattern is four times the intensity due to each slit. Reason : Intensity is directly proportional to square of amplitude. (1) Both Assertion and Reason are cor- rect and Reason is the correct explana- tion of the Assertion. (2) Both Assertion and Reason are cor- rect but Reason is not the correct explana- tion of the Assertion. (3) Assertion is cor- rect but Reason is incorrect. (4) Assertion is incor- rect but reason is correct. 3. The Brewsters angle for an interface should be: (1) (2) (3) (4) 4. Assertion : If the phase difference between the light waves emerging from the slits of the Young's experi‐ ment is radian. The central fringe will be dark. Reason : Phase difference and path difference are not related. (1) Both Assertion and Reason are cor- rect and Reason is the correct explana- tion of the Assertion. (2) Both Assertion and Reason are cor- rect but Reason is not the correct explana- tion of the Assertion. (3) Assertion is cor- rect but Reason is incorrect. (4) Assertion is incor- rect but reason is correct. 5. Assertion : All bright interference bands have the same in‐ tensity. Reason : In interference all bands receive same light from two sources. (1) Both Assertion and Reason are cor- rect and Reason is the correct explana- tion of the Assertion. (2) Both Assertion and Reason are cor- rect but Reason is not the correct explana- tion of the Assertion. (3) Assertion is cor- rect but Reason is incorrect. (4) Assertion is incor- rect but reason is correct. 6. A paralled beam of light of wavelength gets diffracted by a single slit of width . The angular position of the first minima of diffracted light is (1) (2) (3) (4) β = λD d ib 30 ∘ < ib < 45 ∘ 45 ∘ < ib < 90 ∘ ib = 90 ∘ 0 ∘ < ib < 30 ∘ π 6000 o A 0.3 mm 2 × 10 −3 rad 3 × 10 −3 rad 1.3 × 10 −3 rad 6 × 10 −3 rad
7. The diameter of objective of a telescope is . Its resolving limit for the light of wavelength will be (1) (2) (3) (4) None of these 8. A polaroid is placed at to an incoming light of intensity . Now the intensity of light passing through polaroid after polarisation would be (1) (2) (3) (4) Zero 9. An air gap of thickness is present infront of a slit as shown in the figure. The gap between the slits and the screen is filled with a liquid of re‐ fractive index . The path difference between and is (1) (2) (3) (4) 10. In young’s double slit experiment, if the separa‐ tion between coherent sources is halved and the distance of the screen from the coherent sources is doubled, then the fringe width becomes: (1) half (2) four times (3) one-fourth (4) double 11. A telescope of diameter uses light of wave‐ length for viewing stars. The minimum angular separation between two stars whose im‐ age is just resolved by this telescope is (1) (2) (3) (4) 12. Assertion : In everyday life the Doppler's effect is observed readily for sound waves than light waves. Reason : Velocity of light is greater than that of sound. (1) Both Assertion and Reason are cor- rect and Reason is the correct explana- tion of the Assertion. (2) Both Assertion and Reason are cor- rect but Reason is not the correct explana- tion of the Assertion. (3) Assertion is cor- rect but Reason is incorrect. (4) Assertion is incor- rect but reason is correct. 13. Assertion : For best contrast between maxima and minima in the interference pattern of Young's double slit ex‐ periment, the intensity of light emerging out of the two slits should be equal. Reason : The intensity of interference pattern is propor‐ tional to amplitude. (1) Both Assertion and Reason are cor- rect and Reason is the correct explana- tion of the Assertion. (2) Both Assertion and Reason are cor- rect but Reason is not the correct explana- tion of the Assertion. (3) Assertion is cor- rect but Reason is incorrect. (4) Assertion is incor- rect but reason is correct. 14. Two polaroid and are placed in such a way that the pass-axis of polaroids are perpendicular to each other. Now, another polaroid is placed between and bisecting angle between them. If intensity of unpolarized light is then inten‐ sity of transmitted light after passing through po‐ laroid will be (1) (2) Zero (3) (4) 15. In Young’s double - slit experiment, how many maximas can be obtained on a screen (including the central maximum) on both sides of the cen‐ tral fringe ? (1) 7 (2) 12 (3) 4 (4) 18 16. If the slits in Young’s double slit experiment are of unequal width, then (1) The bright fringes will have unequal spacing (2) The bright fringes will have unequal brightness (3) The fringes do not appear (4) The dark fringes are not perfectly dark. 17. Assertion : One of the condition for interference is that the 1m 4538 ∘ A 2.54 × 10 −4 rad 5.54 × 10 −7 rad 6.54 × 10 −7 rad 30 ∘ I0 3I0/4 I0/4 I0 t μ1 S1P S2P + t(μ1 − 1) yd D μ1 yd D μ1 + t(μ1 − 1) yd D t(μ1 − 1) 2m 5000 ∘ A 0.25 × 10 −6 rad 4 × 10 −4 rad 5.0 × 10 −3 rad 0.31 × 10 −6rad A B C A B I0 B I0 8 I0 2 I0 4 (λ = 2000 ∘ A, d = 7000 ∘ A)
two sources should be very narrow. Reason : One broad source is equal to large number of narrow sources. (1) Both Assertion and Reason are cor- rect and Reason is the correct explana- tion of the Assertion. (2) Both Assertion and Reason are cor- rect but Reason is not the correct explana- tion of the Assertion. (3) Assertion is cor- rect but Reason is incorrect. (4) Assertion is incor- rect but reason is correct. 18. Two point white dots are apart on a black paper. They are viewed by eye of pupil diameter . Approximately, what is the maximum dis‐ tance at which dots can be resolved by the eye? (1) (2) (3) (4) 19. If the monochromatic source in Young's double slit experiment is replaced by white light, then (1) Interference pat- tern will disappear (2) There will be a central dark fringe surrounded by a few coloured fringes (3) There will be a central bright white fringe surrounded by a few coloured fringes (4) All bright fringes will be of equal width 20. Assertion : No diffraction is produced in sound waves near a very small opening. Reason : For diffraction to take place the aperture of open‐ ing should be the same order as wavelength of the waves. (1) Both Assertion and Reasons are true and the Reason is a correct explanation of the Assertion. (2) Both Assertion and Reason are true but Reason is not a correct explanation of the Assertion. (3) Assertion is true but the Reason is false. (4) Assertion is false but Reason is true. 21. In the Young's double slit experiment, the inten‐ sity of light passing through each of the two dou‐ ble slits is . The screen slit dis‐ tance is very large in comparison with slit-slit distance. The fringe width is . The distance be‐ tween the central maximum and a point on the screen is . Then the total light intensity at that point is (1) (2) (3) (4) 22. Two transparent slabs are placed infront of two slits in . The path difference between is (1) (2) (3) (4) 23. The interference pattern is obtained with two coherent light sources of intensity ratio . In the interference pattern, the ratio will be (1) (2) (3) (4) 24. Assertion : Corpuscular theory fails in explaining the veloci‐ ties of light in air and water. Reason : According to corpuscular theory, light should travel faster in denser media than in rarer media. (1) Both Assertion and Reasons are true and the Reason is a correct explanation of the Assertion. (2) Both Assertion and Reason are true but Reason is not a correct explanation of the Assertion. (3) Assertion is true but the Reason is false. (4) Assertion is false but Reason is true. 25. The ratio of maximum intensity to the maximum intensity in a diffraction is (1) (2) (3) (4) 1mm 3mm 6 m 3 m 5 m 1 m 2 × 10 −2Wm−2 β P x = β 3 2 × 10 −2Wm−2 16 × 10 −2Wm−2 8 × 10 −2Wm−2 4 × 10 −2Wm−2 Y DSE S1P and S2P + t2(μ2 − 1) yd D t2(μ2 − μ1) yD d [ + t2(μ2 − 1)] − [t1(μ1 − 1)] yd D n Imax−Imin Imax+Imin √n n+1 2√n n+1 √n (n+1) 2 2√n (n+1) 2 2 nd 1 st 4/9 9/25 5/9 25/49