Quiz  /  Optical Instruments MCQ

  • 1. 
    A lens which converges a beam of parallel rays to a point is called

  • Diverging (or concave) lens
  • Converging (or convex) lens
  • Plano concave lens
  • Plano-convex lens

  • 2. 
    The diameter of a lens is called

  • Focal length
  • Principle axis
  • Aperture
  • Radius of curvature

  • 3. 
    In going from a denser to rarer medium a ray of light is

  • Undeviated
  • Bent away from the normal
  • Bent towards the normal
  • polarised

  • 4. 
    The power of a concave lens is

  • Real
  • Virtual
  • Positive
  • negative

  • 5. 
    Magnifying power of a simple microscope

  • Increases with increase in focal length
  • Increases with the decrease in focal length
  • No effect with decrease or increase with the focal length
  • Least distance of distinct vision

  • 6. 
    Magnification of astronomical telescope is

  • f
  • + f
  • f
  • /f
  • f
  • /f
  • (1+f
  • /f
  • )L/f

  • 7. 
    The magnifying power of an astronomical telescope is 10 and the focal length of its eye-piece is 20 cm. The focal length of its objective will be

  • 200 cm
  • 2 cm
  • 0.5 cm
  • 0.5 x 10
  • cm

  • 8. 
    The magnifying power of a telescope is 9. When it is adjusted for parallel rays, the distance between the objective and the eye-piece is found to be 20 cm. The focal lengths of the lenses are

  • 18 cm, 2 cm
  • 11 cm, 9 cm
  • 10 cm, 10 cm
  • 15 cm, 5 cm

  • 9. 
    In a compound microscope, magnifying power is 95 and the distance of the object from the objective lens is 1/38 cm. The focal length of the objective lens ¼ cm. What is the magnification of eyepiece?

  • 5
  • 10
  • 100
  • 200

  • 10. 
    A hypermetropic person having “near point” at a distance of 0.75 m puts on spectacles of power 2.5 D. The “near point” now is at

  • 0.75 m
  • 0.83 m
  • 0.26 cm
  • 0.26 m
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