Gr Xii Ray Optics Online Test 1

25 Questions | Total Attempts: 14

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Gr Xii Ray Optics Online Test 1

25 Questions 50 minutes


Questions and Answers
  • 1. 
    Identify the device.    Ans is ____________.
  • 2. 
    Identify the phenomenon. 
  • 3. 
    Identify the phenomenon
  • 4. 
    Identify the phenomenon
  • 5. 
    A converging lens is used to form an image on a screen. When the upper half of the lens is covered by an opaque screen.
    • A. 

       half the image will disappear.

    • B. 

      Incomplete image will be formed.

    • C. 

      Intensity of image will decrease but complete image is formed.

    • D. 

      Intensity of image will decrease but complete image is formed.

  • 6. 
    In optical fibres, the refractive index of the core is
    • A. 

      Greater than that of the cladding.

    • B. 

       equal to that of the cladding.

    • C. 

      Smaller than that of the cladding.

    • D. 

      Independent of that of cladding.

  • 7. 
    An object is placed at a distance of 0.5 m in front of a plane mirror. The distance between object and image will be
    • A. 

      0.25 m

    • B. 

       0.5 m

    • C. 

       1.0 m

    • D. 

      2.0 m

  • 8. 
    We combine two lenses, one is convex and other is concave having focal lengths f1, and f2 and their combined focal length is F. Combination of the lenses will behave like concave lens, if
    • A. 

       f1 > f2

    • B. 

       f1 = f2

    • C. 

      F1 < f2.

    • D. 

      F1 ≤ f2

  • 9. 
    Tom’ lenses of focal lengths ± 15 cm and ± 150 cm are available for making a telescope. To produce the largest magnification, the focal length of the eyepiece should be
    • A. 

      + 15 cm

    • B. 

       + 150 cm

    • C. 

      – 150 cm

    • D. 

      – 15 cm

  • 10. 
    A convex lens and a concave lens, each having the same focal length of 25 cm, are put in contact to form a combination of lenses. The power of the combination (in dioptres) is
    • A. 

      Zero

    • B. 

      25

    • C. 

      50

    • D. 

      Infinity

  • 11. 
    The refractive index of the material of an equilateral prism is √3. What is the angle of minimum deviation?
    • A. 

      45°

    • B. 

      60°

    • C. 

      37°

    • D. 

      30°

  • 12. 
    The astronomical telescope consists of objective and eyepiece. The focal length of the objective is
    • A. 

      Equal to that of the eyepiece.

    • B. 

      Shorter than that of eyepiece.

    • C. 

      Greater than that of eyepiece.

    • D. 

      Five times shorter than that of eyepiece.

  • 13. 
    For a total internal reflection, which of the following is correct?
    • A. 

       Light travels from rarer to denser medium.

    • B. 

      Light travels from denser to rarer medium.

    • C. 

      Light travels in air only.

    • D. 

      Light travels in water only.

  • 14. 
     Which of the following forms a virtual and erect image for all positions of the object?
    • A. 

      Concave lens

    • B. 

      Option 2

    • C. 

       Convex mirror

    • D. 

      Both (a) and (c)

  • 15. 
    Which of the following colours of white light deviated most when passes through a prism?
    • A. 

      Red light

    • B. 

      Violet light

    • C. 

      Yellow light

    • D. 

      Both (a) and (b)

  • 16. 
    An object is immersed in a fluid. In order that the object becomes invisible, it should
    • A. 

      Behave as a perfect reflector

    • B. 

      Absorb all light falling on it.

    • C. 

      Have refractive index one.

    • D. 

      Have refractive index exactly matching with that of the surrounding fluid.

  • 17. 
    Linear magnification, m=-1. With this information we can say that
    • A. 

      Image is real & enlarged

    • B. 

      Real & same size as object

    • C. 

      Real & diminished

    • D. 

      Virtual & same size as object 

  • 18. 
    The direction of ray of light incident on a concave mirror is shown by PQ while directions in which the ray would travel after reflection is shown by four rays marked 1, 2, 3 and 4. Which of the four rays correctly shows the direction of reflected ray? 
    • A. 

      Ray 1

    • B. 

      Ray 2

    • C. 

      Ray 3

    • D. 

      Ray 4

  • 19. 
    The optical density of turpentine is higher than that of water while its mass density is lower. Figure shows a layer of turpentine floating over water in a container. For which one of the four rays incident on turpentine in figure the path shown is correct?
    • A. 

      Ray 1

    • B. 

      Ray 2

    • C. 

      Ray 3

    • D. 

      Ray 4

  • 20. 
    Consider an extended object immersed in water contained in a plane trough. When seen from close to the edge of the trough the object looks distorted. Which of the following is not correct.
    • A. 

      The apparent depth of the points close to the edge are nearer the surface of the water compared to the points away from the edge.

    • B. 

      The angle subtended by the image of the object at the eye is smaller than the actual angle subtended by the object in air.

    • C. 

      Some of the points of the object far away from the edge may not be visible because of total internal reflection.

    • D. 

      Water in a trough acts as a lens and magnifies the object.

  • 21. 
    We're standing between the focal point of a concave mirror and the mirror. What do we see? -> enlarged, upright, virtual image
    • A. 

      True

    • B. 

      False

  • 22. 
    Light moves from a medium with a high index of refraction to one with a low index of refraction. The light will: -> will experience total internal reflection
    • A. 

      True

    • B. 

      False

  • 23. 
    The magnification factor of an upside down image is -> either positive or negative
    • A. 

      True

    • B. 

      False

  • 24. 
    The line that passes through the center of a curved mirror is called
    • A. 

      Focal point

    • B. 

      Principal axis

    • C. 

      Center of curvature

    • D. 

      Optic center

  • 25. 
    Identify the device
    • A. 

      Compound microscope- adjusted for image at infinity

    • B. 

      Compound microscope- adjusted for image at least distance of distinct vision

    • C. 

      Telescope- normal adjustment

    • D. 

      Telescope- adjusted for distinct vision

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