Tiêu đề 24. Ray Optics And Optical Instruments.pdf ✅

1. A man moves towards a plane mirror with a velocity v in a direction making an angle  with the normal to the mirror. The magnitude of velocity of the image relative to man normal to mirror will be (1) 2 v (2) 2 v cos (3) 2 v sin (4) 2v/cos 2. A concave mirror gives an image three times as large as the object placed at a distance of 20cm from it. For the image to be real, the focal length should be - (1) –10 cm (2) –15 cm (3) –20 cm (4) –30 cm 3. A light beam is travelling from Region I to Region IV (refer figure). The refractive index in Region I , II , III and IV are respectively. The angle of incidence  for which the beam just misses entering Region IV is :- 4. A narrow parallel beam of light is incident paraxially on a solid transparent sphere of radius r kept in air. What should be the refractive index if the beam is to be focused at the farther surface of the sphere. (1) 1.5 (2) 2 (3) 1. 3 (4) None 5. The cross section of a glass prism has the formof an equilateral triangle. A ray is incident ontoone of the faces perpendicular to it. Find the anglebetween the incident ray and the ray that leavesthe prism. The refractive index of glass is μ = 1.5. (1) = 60° (2) = 30° (3) = 45° (4) = 75° 6. An object O is kept infront of a converging lensof focal length 30 cm behind which there is a planemirror at 15 cm from the lens as shown in thefigure. (A) The final image is formed at 60 cm from thelens towards right of it (B) The final image is at 60 cm from lens towardsleft of it (C) The final image is real (D) The final image is virtual. (1) A,C (2) B,C (3) A,D (4) B,D A. If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion. B. If both Assertion & Reason are True but Reasonis not a correct explanation of the Assertion. C. If Assertion is True but the Reason is False. D. If both Assertion & Reason are False. 7. Assertion :- A point object moves near the principal axis of a fixed spherical mirror along astraight line. Then the image formed by thespherical mirror also moves along a straight line. Reason :- For an incident ray on a fixed sphericalmirror there is a fixed reflected ray. If a pointobject moves along this incident ray, its image willalways lie on the given reflected ray. Further an incident ray can be drawn from the moving pointobject in its direction of velocity towards themirror. (1) A (2) B (3) C (4) D 8. A transparent solid cyclindrical rod has a refractive index of 2 3 . It is surrounded by air.A light ray is incident at the mid-point of one endof the rod as shown in the figure. The incident angle  for which the light ray grazesalong the wall of the rod is :- Ray Optics and Optical Instruments
9. An object 2.4 m in front of a lens forms a sharpimage on a film 12 cm behind the lens. A glass plate1 cm thick, of refractive index 1.50 is interposedbetween lens and film with its plane faces parallelto film. At what distance (from lens) should object be shifted to be in sharp focus on film ? (1) 5.6 m (2) 7.2 m (3) 2.4 m (4) 3.2 m 10. Figure shows a mixture of blue, green and redcoloured rays incident normally on a right angledprism. The critical angles of the material of theprism for red, green and blue are 46o, 44o and 43orespectively. The arrangement will separate (1) greencolour from red and blue (2) all the three colours (3) redcolour from blue and green (4) bluecolour from red and green 11. Two convex lenses of focal lengths f1 and f2 aremounted coaxially separated by a distance. If thepower of the combination is zero, the distancebetween the lenses is 12. An object is moving towards a concave mirror offocal length 24 cm. When it is at a distance of60 cm from the mirror its velocity is 9 cm/sec. Thespeed of its image at that instant, is (1) 4 cm/sec towards the mirror (2) 9 cm/sec towards the mirror (3) 4 cm/sec away the mirror (4) 9 cm/sec away the mirror 13. A, B and C are three optical media of respectivecritical angles C1, C2 and C3. Total internalreflection of light can occur from A and B and alsofrom B to C but not from C to A. Then the correctrelation between critical angles is (1) C1> C2> C3 (2) C1 = C2 = C3 (3) C3> C1> C2 (4) C1< C2< C3 14. A hollow concave lens is made of very thintransparent material. It can be filled with air or either of two liquids L1 or L2 having refractive indices n1and n2 respectively (n2> n1> 1). The lens will diverge a parallel beam of light if it is, filled with (1) air and placed in air (2) air and immersed in L1 (3) L1 and immersed in L2 (4) L2 and immersed in L1 15. In a compound microscope, the focal length of twolenses are 1.5 cm and 6.25 cm. If an object isplaced at 2 cm from objective and the final imageis formed at 25 cm from eye lens the distancebetween two lenses is - (1) 6.00 cm (2) 7.75 cm (3) 9.25 cm (4) 11.0 cm 16. A vessel of depth x is half filled with oil of refractive index μ1 and other half is filled withwater of refractive index μ2. The apparent depthof the vessel when viewed from above is – 17. The angle of a prism is ‘A’. One of its refractingsurfaces is silvered. Light rays falling at an angleof incidence 2A on the first surface returns backthrough the same path after suffering reflectionat the silvered surface. The refractive index μ, ofthe prism is :- (1) 2sinA (2) 2cos A (3) 1 cos 2 A (4) tanA 18. Two plane mirrors are placed parallel to each otherat a distance L apart. A point object O placedbetween them at a distance L/3 from one mirror,both mirrors form multiple images. The distancebetween any two images cannot be –
19. A ray of light is incident at 60o on one face of aprism of angle 30o and emergent raymade 30o withincident ray. The refractive index of the prism is - (1) 1.732 (2)1.414 (3) 1.5 (4) 1.33 20. Two lenses of power +10D and –5D are placedin contact. Where should an object be held fromthe lens. So as to obtain a virtual image ofmagnification 2 ? (1) 5 cm (2) –5cm (3) 10 cm (4) –10 cm 21. The apparent depth of a needle lying at the bottomof the tank, which is filled with water of refractiveindex 1.33 to a height of 12.5 cm is measured bya microscope to be 9.4 cm. If water is replacedby a liquid of refractive index 1.5 upto the sameheight. What distance would the microscope haveto be moved to focus on the needle again ? (1) 1.1 cm (2) 2.13 cm (3) 3.1 cm (4) 4.15 cm 22. A convex refracting surface of radius of curvature20 cm separates two media of refractive indices 4 3 and 1.6. An object is placed in the first medium(μ = 4/3) at a distance of 200 cm from therefractingsurface. The position of the imageformed is - (1) 120 cm (2) 240 cm (3) 100 cm (4) 60 cm 23. A short linear object of length b lies along the axisof a concave mirror of focal length f at a distance ufrom the pole of the mirror. What is the size of image? 24. A bucket of total height 60 cm is half filled witha liquid of refractive index 1.5 and half withanother liquid of refractive index 2. The apparentdepth of the bucket for an observer directly abovethe bucket– (1) 45 cm (2) 30 cm (3) 35 cm (4) 45 cm 25. When an object is at a distance x and y from theoptical centre of a lens, a real and a virtual imageare formed, respectively with same magnification.The focal length of lens is– (1) x + y (2) (x + y) / 2 (3) x + y / 2 (4) xy 26. A doctor advises a patient to use spectacles witha convex lens of focal length 40 cm in contact witha concave lens of focal length 25 cm. What is the power of the resultant combination– (1) 1.5 D (2) –1.5 D (3) 6.5 D (4) –6.5 D 27. An astronomical telescope has an angular magnification of magnitude 5 for distant objects.The separation between the objective andeye-piece is 36 cm and the final image is formedat infinity. Determine the focal length of objective and eye-piece– (1) f0 = 30 cm, fe = 6 cm (2) f0 = 25 cm, fe = 10 cm (3) f0 = 30 cm, fe = 10cm (4) f0 = 15 cm, fe = 5 cm 28. When the rectangular metal tank is filled up to thetop with an unknown liquid, an observer with eyeslevel with the top of the tank can just see the cornerE. Find the index of refraction of the liquid :- (1) 1.5 (2) 1.25 (3) 1.67 (4) 2.4 29. The power of a lens having refractive index 1.25is + 3D. When placed in a liquid
its power is–2D. The refractive index of the liquid is :- (1) 1.2 (2) 1.4 (3) 1.5 (4) 1.6 30. A ray of light undergoes a deviation of 30° whenincident on a equilateral prism of refractive index 2 . What is the angle subtended by the ray insidethe prism with the base of the prism– (1) 0° (2) 45° (3) 60° (4) 90° 31. If a person cannot see objects beyond 40 cm, thenpower and type of lens by which he can clearlysee distant objects is– (1) –2.5 D and concave lens (2) –2.5 D and convex lens (3) –3.5 D and concave lens (4) –3.5 D and convex lens 32. A ray of light is incident at the glass-water interface at an angle i, it emerges finally parallelto the surface of water, then the value of g wouldbe – (1) (4/3) sin i (2) 1/sin i (3) 4/3 (4) 1 33. A square card of side length 1 mm is being seenthrough a magnifying lens of focal length 10 cm.The card is placed at a distance of 9 cm fromthe lens. Axis is perpendicular to the plane of card.The apparent area of the card through the lensis (1) 1 cm2 (2) 0.81 cm2 (3) 0.27 cm2 (4) 0.60 cm2 34. The resolving power of an astronomical telescopeis 0.2 sec. If the central half portion of the objectivelens is covered, the resolving power will be (1) 0.1 sec (2) 0.2 sec (3) 1.0 sec (4) 0.6 sec 35. An astronomical telescope has an angular magnification of magnitude 5 for distant objects.The separation between the objective and theeye-piece is 36 cm. The final image is formedat infinity. The focal length fo of the objectiveand fe of the eye- piece are (1) 45 cm and -9 cm (2) 50 cm and 10 cm (3) 7.2 cm and 5 cm (4) 30 cm and 6 cm 36. Two transparent slabs have the same thickness.One is made of material X of refractive index1.5. The other is made of two material Y and Zhaving thickness in the ratio 1 : 2. The refractiveindex of Z is 1.6. If a monochromatic parallelbeam passing through the slabs has the same number of wavelengths inside both, the refractiveof Y is – (1) 1.1 (2) 1.2 (3) 1.3 (4) 1.4 37. Bob of a pendulum is left from position P, velocityof image on mirror M of bob at position Qwr tobob is – 38. For a small angled prism, angle of prism A, theangle of minimum deviation () varies withthe refractive index of the prism as shown in thegraph. (1) Point P corresponds to  = 1/2 (2) Slope of the line PQ = A/2 (3) Slope = A (4) None of the above statements is true 39. A concave mirror of focal length 'f1' is placed ata distance of 'd' from a convex lens of focal length'f2'. A beam of light coming from infinity andfalling on this convex lens concave mirrorcombination