CBSE  /  Class 12  /  Physics  /  Ray Optics and Optical Instruments

  • 1. 
    A concave mirror of focal length f produces an image n times the size of the object. If the image is real then the distance of the object is:

  • (n - 1) f
  • (n + 1) f
  • (\(\frac{n+1}{n}\))f
  • (\(\frac{n-1}{n}\)f

  • 2. 
    A convergent lens will become less convergent in :

  • oil
  • water
  • both of (a) and (b)
  • none of these

  • 3. 
    A thin glass (RI = \(\frac{3}{2}\)) lens has optical power of - 5D in air. Its optical power in a liquid medium with RI = 1.6 will be:

  • -2.5 D
  • 25 D
  • -ID
  • 0.625 D

  • 4. 
    On reflection from a denser medium, a light wave suffers a phase difference of:

  • π
  • \(\frac{π}{2}\)
  • \(\frac{π}{4}\)
  • 2π

  • 5. 
    The branch of optics dealing with the formation of images using the concept of straight line propagation of light is called:

  • geometrical optics
  • physical optics
  • corpuscular optics
  • quantum optics

  • 6. 
    When light travels from one medium to another, which of the following does not change?

  • frequency
  • refractive index
  • velocity
  • wavelength

  • 7. 
    Two lens of power -15 D and +5 D are placed in contact co-axially. The focal length of equivalent lens is:

  • -10 cm
  • -20 cm
  • +10 cm
  • None

  • 8. 
    Refractive index of water and glass are \(\frac{4}{3}\) and \(\frac{5}{3}\). A light ray is going to water from glass. Then, its critical angle will be:

  • sin-1\(\frac{4}{5}\)
  • sin-1\(\frac{5}{6}\)
  • sin-1\(\frac{1}{2}\)
  • sin-1(\(\frac{2}{1}\))

  • 9. 
    The air bubble inside water shine due to:

  • Reflection
  • Refraction
  • T.l.R.
  • None of these

  • 10. 
    When a ray of light (white) enters a lens, undergoes a change is:

  • wavelength
  • velocity
  • frequency
  • both velocity and wavelength
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