Ray Optics And Optical Instruments

15 Questions | Total Attempts: 1203

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Ray Optics And Optical Instruments

Time: 30 Minute


Questions and Answers
  • 1. 
    The absolute refractive indices of water and glass are 1.3 and 1.5 respectively. The refractive index of water w.r.t. glass is
    • A. 
    • B. 
    • C. 
    • D. 

      None of these

  • 2. 
    The focal length of the lens is 50 cm; then its power is
    • A. 

      + 1 D

    • B. 

      + 2 D

    • C. 

      – 2 D

    • D. 

      – 1 D

  • 3. 
    A convex mirror has a focal length f. A real object, placed at a distance f in front of it from the pole, produces an image at
    • A. 

      F

    • B. 
    • C. 

      2f

    • D. 

      Infinity

  • 4. 
    A convex lens of focal length x and a concave lens of focal length y are placed in contact. The focal length of the combination is
    • A. 

      X + y

    • B. 

      X - y

    • C. 
    • D. 
  • 5. 
    What should be the refractive index of a completely transparent medium for it to be visible in vacuum?
    • A. 

      1

    • B. 

      Less than 1

    • C. 

      Greater than 1

    • D. 

      None of the above

  • 6. 
    A graph is plotted between the angle of incidence (i) and angle of reflection (r). The correct variation is shown by
    • A. 
    • B. 
    • C. 
    • D. 
  • 7. 
    Rainbow is formed due to combination of:
    • A. 

      Refraction and absorption

    • B. 

      Dispersion and foccusing

    • C. 

      Refraction and scattering

    • D. 

      Dispersion and total internal reflection

  • 8. 
    Figure shows three cases of a ray passing through a prism of refracting edge A. The case corresponding to minimum deviation is
    • A. 
    • B. 
    • C. 
    • D. 

      None of these

  • 9. 
    The plane face of a plano-convex lens of focal length 20 cm is silvered as shown in Figure. What kind of a mirror will it behave?
    • A. 

      Convex, f = 20 cm

    • B. 

      Convex, f = 10 cm

    • C. 

      Concave, f = 20 cm

    • D. 

      Concave, f = 10 cm

  • 10. 
    If a water drop is kept between two glass plates, then its surface is correctly shown by
    • A. 
    • B. 
    • C. 
    • D. 
  • 11. 
    A telescope has an objective lens of 10 cm diameter and is situated at a distance of 1 km from two objects. The minimum distance between theses two objects, which can be resolved by the telescope, when the mean wavelength of light is 5000 Ǻ is of order of:
    • A. 

      5 mm

    • B. 

      5 cm

    • C. 

      2.5 m

    • D. 

      5 m

  • 12. 
    A glass prism of refractive index 1.5 is immersed in water (refractive index 4/3). A light beam incident normally on the face AB is totally reflected to reach the face BC if:
    • A. 

      Sin C = 8/9

    • B. 

      Sin C = 9/8

    • C. 

      Sin C = 2/3

    • D. 

      Sin C = 3/2

  • 13. 
    Focal length of a glass lens in air is 2 cm. Its focal length when immersed in water would be
    • A. 

      4cm

    • B. 

      6cm

    • C. 

      8 cm

    • D. 

      12 cm

  • 14. 
    In an experiment to find focal length of a concave mirror, a graph is drawn between the magnitude of u and v. The graph looks like:
    • A. 
    • B. 
    • C. 
    • D. 
  • 15. 
    If a beam of light passes from air to glass, the speed of light
    • A. 

      Decreases

    • B. 

      Increases

    • C. 

      Remains unchanged

    • D. 

      It may increases or decrease depending upon the colour