1. OPTICS-PART TEST - 1-PHYSICS

PART TEST - 1 (PT-1) TOPIC : OPTICS (PHYSICS) Duration : 1 Hour Max. Marks : 90 GENERAL INSTRUCTIONS 1. This Question Paper contains 30 objective type questions. 2. Each question has 4 choices (A), (B), (C) and (D), out of which only one is correct. 3. For each question, you will be awarded 3 Marks if you give the correct answer and zero Mark if no answer is given. In all other cases, minus one (–1) Mark will be awarded. SECTION - I Straight Objective Type This section contains 30 Single choice questions. Each question has choices (A), (B), (C) and (D), out of which ONLY ONE is correct. 1. A uniform, horizontal parallel beam of light is incident upon a prism as shown. The prism is in the shape of a quarter cylinder, of radius R = 5 cm, and has the index of refraction n = 5/3. The width of the region at which the incident rays after normal incidence on plane surface and subsequent refraction at curved surface intersect on x axis is (Neglect the ray which travels along x-axis as shown in figure) (A) 4 cm (B) 5/4 cm (C) 9/4 cm (D) 25/4cm 2. Inside a solid glass sphere of radius R  a point source of light lies at a distance x ( x < R) from centre of the sphere. The solid sphere is surrounded by air of refractive index 1. The maximum angle of incidence for rays incident on the spherical glass- air interface directly from the point source is: x (A) cos–1 R x (B) sin–1 R (C) cos–1 (D) sin–1 3. Two transparent slabs are of equal length (thickness). One is made of a material A of R.I. 1.5 and the other is made of materials B and C, the ratio of their thickness being 1: 2. The R.I. of C is 1.6. When light passes through them, the two slabs have the same number of waves. The R.I. of B is (Light is incident normally) (A) 1.4 (B) 1.3 (C) 1.1 (D) 1.05 11. In the figure shown a convex mirror of radius of curvature 20 cm is shown. An object O is placed in front of this mirror. Its ray diagram is shown. How many mistakes are there in the ray diagram (AB is its principal axis): (A) 3 (B) 2 (C) 1 (D) 0 12. For a real object, all of the following statements are correct except : (A) the magnification produced by a convex mirror is always less than one (except at the pole) (B) a virtual, erect, same sized image can be obtained by using a plane mirror (C) a virtual, erect, magnified image can be formed using a concave mirror (D) a real, inverted, same sized image can be formed using a convex mirror. 13. In the figure shown find the total magnification after two successive reflections first on M1 & then on M2 (A) + 1 (B) – 2 (C) + 2 (D) – 1 14. A particle revolves in clockwise direction (as seen from point A) in a circle C of radius 1 cm and completes one revolution in 2 sec. The axis of the circle and the principal axis of the mirror M coincide. Call it AB. The radius of curvature of the mirror is 20 cm. Then the direction of revolution (as seen from A) of the image of the particle and its speed is (A) Clockwise, 1.57 cm/s (B) Clockwise, 3.14 cm/s (C) Anticlockwise, 1.57 cm/s (D) Anticlockwise, 3.14 cm/s 15. The relative refractive index of glass with respect to a material is 0.9 and the absolute refractive index of glass is 1.512. The refractive index of the material is (A) 1.42 (B) 1.58 (C) 1.68 (D) 1.72 16. A lens of focal length 20.0 cm and aperture radius 2.0 cm is placed at a distance 30.0 cm from a point source of light. On the other side a screen is placed at a distance 50.0 cm from the lens. The radius of spot of light formed on screen is. (Neglect spherical abberation through lens) 1 (A) 2 1 cm (B) 3 1 cm (C) 5 cm (D) 1.0 cm 17. A convex lens is cut into two parts in different ways that are arranged in four manners, as shown. Which arrangement will give maximum optical power ? (A) (B) (C) (D) 28. A point source of light is kept at the centre of a solid transparent sphere. The sphere is surrounded by air . The refractive index of material of sphere for which the rays incident from point source on glass–air interface will suffer total internal reflection is: (A) 1.5 (B) (C) 2 (D) Total internal reflection will not occur for any value of refractive index of the sphere. 29. A point object ' O ' is at the centre of curvature of a concave mirror. The mirror starts to move at a speed u, in a direction perpendicular to the principal axis. Then the initial velocity of the image is: (A) 2 u, in the direction opposite to that of mirror's velocity (B) 2 u, in the direction same as that of mirror's velocity (C) zero (D) u, in the direction same as that of mirror's velocity. 30. In the figure shown an object ‘AB’ makes small angle with the normal line ‘PQ’. The length of ‘AB’ is 𝑙 . The refractive index of the slab is ‘n’ and the surrounding medium is air. ‘AB’ is seen with the help of paraxial rays, from the left side of the slab. The size of the image of AB is 𝑙 (A) 𝑙 (B)   1  (C) 𝑙 (D) 𝑙 1     PART TEST - 2 (PT-2) TOPIC : OPTICS Duration : 1 Hour Max. Marks : 90 GENERAL INSTRUCTIONS 1. This Question Paper contains 24 questions. 2. For each question in Section I , you will be awarded 3 Marks if you give the correct answer and zero Mark if no answer is given. In all other cases, minus one (–1) Mark will be awarded. 3. For each question in Section II , you will be awarded 4 Marks if you give the correct answer. There is no negative marking. 4. For each question in Section III, you will be awarded 3 Marks if you give the correct answer and zero Mark if no answer is given. In all other cases, minus one (–1) Mark will be awarded. 5. For each question in Section IV, you will be awarded 4 Marks if you give the correct answer and zero Mark if no answer is given. In all other cases, minus one (–1) Mark will be awarded. 6. For each question in Section V, you will be awarded 6 Marks if you give ALL the correct answer(s) or awarded : (i) 1 Mark for correct answer in one row. (ii) 2 Marks for correct answer in two rows. (iii) 4 Marks for correct answer in three rows. SECTION - I Straight Objective Type This section contains 8 Single choice questions. Each question has choices (A), (B), (C) and (D), out of which ONLY ONE is correct. 1. An interference is observed due to two coherent sources 'A' & 'B' having phase constant zero, separated by a distance 4  along the y  axis where  is the wavelength of the sources. A detector D is moved on the positive x  axis. The number of points on the x  axis excluding the points, x = 0 & x =  at which maximum will be observed are (A) three (B) four (C) two (D) infinite 2. The observer 'O' sees the distance AB as infinitely large. If refractive 1 index of liquid is 1 and that of glass is 2, then  2 is : (A) 2 (B) 1/2 (C) 4 (D) None of these 10. A parallel beam of light (  Å is incident at an angle  = 30° with the normal to the slit plane in a young’s double slit experiment. Assume that the intensity due to each slit at any point on the screen is 0. Point O is equidistant from S1 & S2.The distance between slits is 1mm. (A) the intensity at O is 40 (B) the intensity at O is zero (C) the intensity at a point on the screen 4m from O is 40 (D) the intensity at a point on the screen 4m from O is zero 11. Figure shows two thin slabs of glass, one is rectangular and the other is triangular wedge shaped. A monochromatic light incident nearly normally on the slabs as shown in figure. (A) In situation (X) fringes are thinner as compared to fringes obtained in situation (Y) (B) In case (X) no fringes are obtained and in case (Y) fringes are obtained (C) The shape of the fringe obtained is circular. (D) The shape of the fringe obtained is straight line. 12. A Young’s double slit experiment is conducted in water ( ) as shown in the figure and a glass plate of thickness t and refractive index  is placed in the path of S . The magnitude of the phase difference at O is (Assume that ‘’ is the wavelength of light in air). O is symmetrical with respect to S and S . (A)  2    1t (B)  1    1 t  1  2  2  2 (C) |(2 – 1) t|  (D) |(2 – 1) t |  SECTION - III Reasoning Type This section contains 4 Reasoning type questions. Each question has 4 choices (A), (B), (C) and (D), out of which ONLY ONE is correct. 13. Statement-1 : Two coherent point sources of light having nonzero phase difference are separated by small distance. Then on the perpendicular bisector of line segment joining both the point sources, constructive interference cannot be obtained. Statement-2 : For two waves from coherent point sources to interfere constructively at a point, the magnitude of their phase difference at that point must be 2m  where m is a nonnegative integer) . (A) Statement-1 is True, Statement-2 is True; Statement-2 is a correct explanation for Statement-1 (B) Statement-1 is True, Statement-2 is True; Statement-2 is NOT a correct explanation for Statement-1 (C) Statement-1 is True, Statement-2 is False (D) Statement-1 is False, Statement-2 is True. SECTION - IV Comprehension Type This section contains 2 Paragraphs. Based upon each paragraph, 3 Multiple choice questions have to be answered. Each question has 4 choices (A), (B), (C) and (D), out of which ONLY ONE is correct. Paragraph for Question Nos. 17 to 19 In the figure an arrangement of young's double slit experiment is shown. A parallel beam of light of wavelength '' (in medium n ) is incident at an angle '' as shown. Distance S O = S O. Point 'O' is the origin of the coordinate system. The medium on the left and right side of the plane of slits has refractive index n1 and n2 respectively. Distance between the slits is d. The distance between the screen and the plane of slits is y n1 n2 S1  O x D. Using D = 1m, d = 1mm,  = 30°,  = 0.3mm, n = answer the following : 4 10 3 , n2 = 9 , S2 D Screen 17. The y-coordinate of the point where the total phase difference between the interefering waves is zero, is (A) y = 0 (B) y = + 3 m 4 (C) y = – 3 m (D) – m 4 18. If the intensity due to each light wave at point 'O' is I0 then the resultant intensity at point 'O' will be - 1 cos 40  (A) Zero (B) 2I   0  9  (C) 3I0 (D)  19. y-coordinate of the nearest maxima above 'O' will be - (A) cm (B) 24 cm (C) cm (D) None of these Paragraph for Question Nos. 20 to 22 The ciliary muscles of eye control the curvature of the lens in the eye and hence can alter the effective focal length of the system. When the muscles are fully relaxed, the focal length is maximum. When the muscles are strained the curvature of lens increases (that means radius of curvature decreases) and focal length decreases. For a clear vision the image must be on retina. The image distance is therefore fixed for clear vision and it equals the distance of retina from eye-lens. It is about 2.5 cm for a grown-up person. 24. A double slit interference pattern is produced on a screen, as shown in the figure, using monochro- matic light of wavelength 500 nm. Point P is the location of the central bright fringe, that is produced when light waves arrive in phase without any path difference. A choice of three strips A, B and C of transparent materials with different thicknesses and refractive indices is available, as shown in the table. These are placed over one or both of the slits, singularly or in conjunction, causing the interfer- ence pattern to be shifted across the screen from the original pattern. In the column-I, how the strips have been placed, is mentioned whereas in the column-II, order of the fringe at point P on the screen that will be produced due to the placement of the strip(s), is shown. Correctly match both the columns. Slit I Slit II P Screen Column - I Column - II (A) Only strip B is placed over slit-I (p) First Bright (B) Strip A is placed over slit-I and strip C is (q) Fourth Dark placed over slit-II (C) Strip A is placed over the slit-I and strip B and (r) Fifth Dark strip C are placed over the slit-II in conjunction. (D) Strip A and strip C are placed over slit-I (in (s) Central Bright conjuction) and strip B is placed over slit-II. PART TEST - 3 (PT-3) TOPIC : OPTICS Duration : 1 Hour Max. Marks : 90 GENERAL INSTRUCTIONS 1. This Question Paper contains 22 questions. 2. For each question in Section I, you will be awarded 3 Marks if you give the correct answer and zero Mark if no answer is given. In all other cases, minus one (–1) Mark will be awarded. 3. For each question in Section II, you will be awarded 4 Marks if you give the correct answer. There is no negative marking. 4. For each question in Section III, you will be awarded 3 Marks if you give the correct answer and zero Mark if no answer is given. In all other cases, minus one (–1) Mark will be awarded. 5. For each question in Section IV, you will be awarded 4 Marks if you give the correct answer and zero Mark if no answer is given. In all other cases, minus one (–1) Mark will be awarded. 6. For each question in Section V, you will be awarded 6 Marks if you give ALL the correct answer(s) or awarded : (i) 1 Mark for correct answer in one row. (ii) 2 Marks for correct answer in two rows. (iii) 4 Marks for correct answer in three rows. 7. For each question in Section VI, you will be awarded 6 Marks if you give the correct answer. There is no negative marking. SECTION - I Straight Objective Type This section contains 8 Single choice questions. Each question has choices (A), (B), (C) and (D), out of which ONLY ONE is correct. 1. An opaque sphere of radius a is just immersed in a transparent liquid as shown in figure. A point source is placed on the vertical diameter of the sphere at a distance a/2 from the top of the sphere. One ray originating from the point source after refraction from the air liquid interface forms tangent to the sphere. The angle of refraction for that particular ray is 30º. The refractive index of the liquid is (A) (B) (C) (D) 7. Two plane mirrors are joined together as shown in figure. Two point objects O1 and O2 are placed symmetrically such that AO1 = AO2. The image of the two objects is common if : (A)  = 60° (B)  = 90° (C)  = 30° (D)  = 45° 8. Monochromatic light rays parallel to x-axis strike a convex lens AB. If the lens oscillates such that AB tilts upto a small angle  (in radian) on either side of y-axis, then the amplitude of oscillation of image will be (f = focal length of the lens) : (A) f sec (B) f sec2 f 2 (C) 2 (D) the image will not move SECTION - II Multiple Correct Answers Type This section contains 4 Multiple choice questions. Each question has 4 choices (A), (B), (C) and (D), out of which ONE OR MORE may be correct. 9. A particle is moving towards a fixed convex mirror. The image also moves. If Vi = speed of image and VO = speed of the object, then (A) Vi  VO if |u| < |F| (B) Vi > VO if |u| > |F| (C) Vi < VO if |u| > |F| (D) Vi = VO if |u| = |F| 10. The speed of light in the material of a plano convex lens is 2 × 108 m/s and its greatest thickness is 3 mm. If the aperture diameter of the lens in 6.0 cm then : (A) focal length of the lens is 6.0 cm. (B) focal length of the lens is 30.4 cm. (C) radius of curvature of the lens is 15.2 cm. (D) parallel rays after falling on the lens converge at a distance of 6.0 cm on the other side of the lens. 11. In displacement method, the distance between object and screen is 96 cm. The ratio of length of two images formed by a convex lens placed between them is 4.84. (A) Ratio of the length of object to the length of shorter image is 11/5. (B) Distance between the two positions of the lens is 36 cm. (C) Focal length of the lens is 22.5 cm. (D) Distance of the lens from the shorter image is 30 cm. 12 Which of the following statements is/are correct about the refraction of light from a plane surface when light ray is incident in denser medium. [C is critical angle] (A) The maximum angle of deviation during refraction is  – C, it will be at angle of incidence C. 2 (B) The maximum angle of deviation for all angle of incidences is  – 2C, when angle of incidence is slightly greater than C. (C) If angle of incidence is less than C then deviation increases if angle of incidence is also increased. (D) If angle of incidence is greater than C then angle of deviation decreases if angle of incidence is increased. 15. The y-coordinates of second order bright formed on the screen is (A) 250 m (B) 500 m (C) – 250 m (D) – 500 m 16. The region on screen where interference pattern is formed lies in (A) –  < y < +  (B) –  < y < 0 (C) 1(m) < y ≤ 0 (D) –1 (m) < y  0 17. The minimum horizontal distance of screen from fixed source such that at least one bright is formed on screen (A) 1 mm (B) 2 mm (C) 1 cm (D) 1 m SECTION - V Matrix - Match Type This section contains 1 questions. Each question has four statements (A, B, C and D) given in Column-I and five statements (p,q,r, s and t) in Column-II. Any given statement in Column-I can have correct matching with ONE OR MORE statement(s) in Column-II. The answers to these questions have to be appropriately marked as illustrated in the following example. If the correct matches are A-p, A-r, B-p, B-s, C-r, C-s, D-q and D-t then the answer should be written as : A  p,r ; B p, s ; C  r, s ; D  q, t. 18. A white light ray is incident on a glass prism, and it create four refracted rays A, B, C and D. Match the refracted rays with the colours given (1 & D are rays due to total internal reflection.): Ray Colour (A) A (p) red (B) B (q) green (C) C (r) yellow (D) D (s) blue SECTION - VI Integer value correct Type This section contains 4 questions. The answer to each question is a integer type. 19. An equiconvex lens of focal length 10 cm (in air) and R.I. 3/2 is put at a small opening on a tube of length 1 m fully filled with liquid of R.I. 4/3. A concave mirror of radius of curvature 20 cm is cut into two halves m1 and m2 and placed at the end of the tube. m1 & m2 are placed such that their principal axes AB and CD respectively are separated by 1 mm each from the principal axes of the lens. A slit S placed in air illuminates the lens with light of frequency 7.5  1014 Hz. The light reflected from m1 and m2 forms interference pattern on the left end EFof the tube. O is an opaque substance to cover the gap left by m1 & m2. The position of the image formed by lens water combination is a × 10–2m from lens and the distance ab between the images formed by m1 & m2 is b × 10–3 m then find 40 . A nswers 1. (D) 2. (B) 3. (C) 4. (D) 5. (A) 6. (D) 7. (B) 8. (C) 9. (A,C) 10. (B,C) 11. (A,B,D) 12 (A,B,C,D) 13. (C) 14. (A) 15. (D) 16. (D) 17. (A) 18. (A) p, (B) r, (C) q, (D) s 19. 8 20. 4 21. 8 m/s 22. 130