Wave Optics PYQs Set 7 (PDF)

Set 7 of 9 · Questions 181-210 of 243

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Mere Teacher · Previous Year Questions NEET Physics · Wave Optics · Set 7 (Q181-210)
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181. $When an unpolarized light falls at a particular angle on a glass plate (placed in air), it is observed that the reflected beam is linearly polarized. The angle of refracted beam with respect to the normal is . , refractive indices of air and glass are 1.00 and 1.52 , respectively.)$ (1) $39.6^{\circ}$ (2) $32.3^{\circ}$ (3) $36.3^{\circ}$ (4) $42.6^{\circ}$ 182. $In young's double slit experiment, the fringe width is 12mm. If the entire arrangement is placed in water of refractive index , then the fringe width becomes (in mm)$ (1) $16$ (2) $9$ (3) $48$ (4) $12$ 183. $In a double-slit experiment, green light (5303Å) falls on a double slit having a separation of 19.44 µm and width of 4.05µm The number of bright fringes between the first and second diffraction minima is:$ (1) $09$ (2) $05$ (3) $04$ (4) $10$ 184. $Consider a tank made of glass (refractive index ) with a thick bottom. It is filled with a liquid of refractive index . A student finds that, irrespective of what the incident angle (see figure) is for a beam of light entering the liquid, the light reflected from the liquid glass interface is never completely polarized. For this to happen, the minimum value of is:$ (1) $\frac{5}{3}$ (2) $\frac{3}{5}$ (3) $\frac{5}{3}$ (4) $\frac{4}{3}$ 185. $For a specific wavelength 670 nm of light coming from a galaxy moving with velocity v, the observed wavelength is 670.7 nm. The value of v is :$ (1) $3 x 1 0^{8} m s^{- 1}$ (2) $3 x 1 0^{10} m s^{- 1}$ (3) $3.13 x 1 0^{5} m s^{- 1}$ (4) $4.48 x 1 0^{5} m s^{- 1}$ 186. $Three polaroid sheets P_{1}, P_{2} and P_{3} are kept parallel to each other such that the angle between pass axes of P_{1} and P_{2} is 45^{\circ} and that between P_{2} and P_{3} is 45^{\circ} . If unpolarised beam of light of intensity 128 W m^{- 2} is incident on P_{1} . What is the intensity of light coming out of P_{3} ?$ (1) $16 W m^{- 2}$ (2) $64 W m^{- 2}$ (3) $128 W m^{- 2}$ (4) $0$ 187. $A light beam is described by E = 800 sin ω (t - \frac{x}{c}) . An electron is allowed to move normal to the propagation of light beam with a speed of 3 \times 1 0^{7} m s^{- 1} . What is the maximum magnetic force exerted on the electron?$ (1) $1.28 \times 1 0^{- 18} N$ (2) $1.28 \times 1 0^{- 21} N$ (3) $12.8 \times 1 0^{- 17} N$ (4) $12.8 \times 1 0^{- 18} N$ 188. $In case of Fraunhoffer diffraction at a single slit the diffraction pattern on the screen is correct for which of the following statements?$ (1) $Central dark band having uniform brightness on either side.$ (2) $Central dark band having alternate dark and bright bands of decreasing intensity on either side.$ (3) $Central bright band having dark bands on either side.$ (4) $Central bright band having alternate dark and bright bands of decreasing intensity on either side.$ 189. $Two polarizers P_{1} and P_{2} are placed in such a way that the intensity of the transmitted light will be zero. A third polariser P_{3} is inserted in between P_{1} and P_{2}, at particular angle between P_{2} and P_{3} . The transmitted intensity of the light passing the through all three polarizers is maximum. The angle between the polarizers P_{2} and P_{3} is:$ (1) $π /6$ (2) $\frac{π}{3}$ (3) $\frac{π}{4}$ (4) $π /8$ 190. $Two poles are separated by a distance of 3.14 m . The resolving power of human eye is 1 minute of an arc. The maximum distance from which he can identify the two poles distinctly is$ (1) $188 m$ (2) $376 m$ (3) $10.8 km$ (4) $5.4 km$ 191. $In a Young's double slit experiment, the ratio of amplitude of light coming from slits is 2 : 1. The ratio of the maximum to minimum intensity in the interference pattern is$ (1) $9 : 4$ (2) $25 : 9$ (3) $2 : 1$ (4) $9 : 1$ 192. $When unpolarized light is incident at an angle of on a transparent medium from air. The reflected ray is completely polarized. The angle of refraction in the medium is$ (1) $30^{\circ}$ (2) $60^{\circ}$ (3) $90^{\circ}$ (4) $45^{\circ}$ 193. $A light is travelling from air into a medium. Velocity of light in a medium is reduced to 0.75 times the velocity in air. Assume that angle of incidence ' i' is very small, the deviation of the ray is$ (1) $i$ (2) $\frac{i}{3}$ (3) $\frac{i}{4}$ (4) $\frac{3 i}{4}$ 194. $The ratio of intensities at two points P and Q on the screen in a Young's double slit experiment where phase difference between two waves of same amplitude are \frac{π}{3} and \frac{π}{2}, respectively are$ (1) $2 : 3$ (2) $1 : 3$ (3) $3 : 1$ (4) $3 : 2$ 195. $In the Young's double slit experiment using a monochromatic light of wavelength λ, the path difference (in terms of an integer n) corresponding to any point having half the peak intensity is :$ (1) $(^{2 n + 1}) \frac{λ}{2}$ (2) $(^{2 n + 1}) \frac{λ}{4}$ (3) $(^{2 n + 1}) \frac{λ}{8}$ (4) $(^{2 n + 1}) \frac{λ}{16}$ 196. $In young's double slit experiment performed using a monochromatic light of wavelength λ, when a glass plate (μ = 1.5) of thickness x λ is introduced in the path of the one of the interfering beams, the intensity at the position where the central maximum occurred previously remains unchanged. The value of x will be:$ (1) $3$ (2) $2$ (3) $1.5$ (4) $0.5$ 197. $A ray of light travelling through rarer medium is incident at very small angle on a glass slab and after refraction its velocity is reduced by . The angle of deviation is$ (1) $\frac{i}{8}$ (2) $\frac{i}{5}$ (3) $\frac{i}{2}$ (4) $\frac{4 i}{5}$ 198. $The figure shows a Young's double slit experimental setup. It is observed that when a thin transparent sheet of thickness and refractive index is put in front of one of the slits, the central maximum gets shifted by a distance equal to fringe widths. If the wavelength of light used is , will be:$ (1) $\frac{2 nDλ}{a ( μ - 1 )}$ (2) $\frac{nλ}{( μ - 1 )}$ (3) $\frac{Dλ}{a ( μ - 1 )}$ (4) $\frac{2 Dλ}{a ( μ - 1 )}$ 199. $Assuming human pupil to have a radius of 0.25 cm and a comfortable viewing distance of 25 cm, the minimum separation between two objects that human eye can resolve at 500 nm wavelength is :$ (1) $1 μm$ (2) $30 μm$ (3) $100 μm$ (4) $300 μm$ 200. $The width of fringe is 2 mm on the screen in a double slit experiment for the light of wavelength of 400 nm. The width of the fringe for the light of wavelength 600 nm will be:$ (1) $4 mm$ (2) $2 mm$ (3) $1.33 mm$ (4) $3 mm$ 201. $In a Young's double slit experiment, the width of the one of the slit is three times the other slit. The amplitude of the light coming from a slit is proportional to the slit-width. Find the ratio of the maximum to the minimum intensity in the interference pattern.$ (1) $4 : 1$ (2) $2 : 1$ (3) $3 : 1$ (4) $1 : 4$ 202. $A transparent medium shows relation between i and r as shown. If the speed of light in vacuum is c, the Brewster's angle for the sin i medium is$ (1) $60^{\circ}$ (2) $30^{\circ}$ (3) $90^{\circ}$ (4) $45^{\circ}$ 203. $n’ polarizing sheets are arranged such that each makes an angle 45° with the proceeding sheet. An unpolarized light of intensity I is incident into this arrangement. The output intensity is found to be \frac{I}{64} . The value of n will be:$ (1) $3$ (2) $6$ (3) $5$ (4) $4$ 204. $P Q represents a wavefront and AO and BP, the corresponding two rays. Find the condition on O for constructive interference at P between ray BP and reflected ray OP .$ (1) $cos θ = \frac{3 λ}{2 d}$ (2) $cos θ = \frac{λ}{4 d}$ (3) $sec θ - cos θ = \frac{λ}{d}$ (4) $sec θ - cos θ = \frac{4 λ}{d} .$ 205. $In the Young's double slit experiment a monochromatic source of wavelength λ is used. The intensity of light passing through each slit is I_{0} . The intensity of light reaching the screen S_{C} at a point P, a distance x from O is given by (Take d ≪ D)$ (1) $I_{0} cos^{2} (\frac{πD}{λd} x)$ (2) $4 I_{0} cos^{2} (\frac{πd}{λD} x)$ (3) $I_{0} sin^{2} (\frac{πd}{2 λD} x)$ (4) $4 I_{0} cos (\frac{πd}{2 λD} x)$ 206. $Consider a Young's double slit experiment as shown in figure. What should be the slit separation d in terms of wavelength λ such that the first minima occurs directly in front of the slit (S_{1}) ?$ (1) $\frac{λ}{2 ( 5 - 2 )}$ (2) $\frac{λ}{( 5 - 2 )}$ (3) $\frac{λ}{2 ( 5 - 2 )}$ (4) $\frac{λ}{( 5 - 2 )}$ 207. $Young’s double slit experiment is carried out by using green, red and blue light, one color at time. The fringe widths recorded are β_{G}, β_{R} and β_{B}, respectively. Then$ (1) $βG > βB > βR$ (2) $βB > βG > βR$ (3) $βR > βB > βG$ (4) $βR > βG > βB$ 208. $A ray of light in vacuum is incident on a glass slab at angle and refracted at angle along as shown in the figure. The optical path length of light ray from to is:$ (1) $\frac{2 3}{a} + 2 b$ (2) $2 a + \frac{2 b}{3}$ (3) $2 a + \frac{2 b}{3}$ (4) $2 a + 2 b$ 209. $Tow beams, A and B, of plane polarized light with mutually perpendicular planes of polarization are seen through a polaroid. From the position when the beam A has maximum intensity (and beam B has zero intensity), a rotation of polaroid through 30º makes the two beams appear equally bright. If the initial intensities of the two beams are I_{A} and I_{B} respectively, then \frac{I _{A}}{I _{B}} equals$ (1) $3$ (2) $\frac{3}{2}$ (3) $1$ (4) $\frac{1}{3}$ 210. $The angular width of the central maximum in a single slit diffraction pattern is 60°. The width of the slit is 1 μm. The slit is illuminated by monochromatic plane waves. If another slit of same width is made near it, Young's fringes can be observed on a screen placed at a distance 50 cm from the slits. If the observed fringe width is 1 cm, what is slit separation distance? (i.e. distance between the centres of each slit.)$ (1) $75 μm$ (2) $100 μm$ (3) $25 μm$ (4) $50 μm$