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

  • 1. 
    For achromatic combination of lenses, if we use two lenses of focal length f' and f1 dipersive power to ω and ω' respectively, then

  • ω = ω0, ω'= 2ω0, f' = 2f
  • ω = ω0, ω' = 2ω0, f' = -2f
  • ω = ω0, ω' = 2ω0, f' = f/2
  • ω = ω0, ω' = 2ω0, f' = -f/2

  • 2. 
    ar point of a myopic eye is 40 cm. The dioptic power of a corrective lens is:

  • 40 D
  • -4 D
  • -2.5 D
  • -0.25 diopter

  • 3. 
    Two thin lenses of focal lengths 20 cm and 25 cm are placed in contact. The effective power of the combination is:

  • 45 D
  • 9 D
  • \(\frac{1}{9}\) D
  • 6 D

  • 4. 
    A blue cross on the white background is illuminated with white light and is observed through red filter. What is seen?

  • A red cross on a black background
  • A blue cross on a red background
  • A red cross on a blue background
  • A black cross on a red background

  • 5. 
    The angle of deviation for a prism is greatest for:

  • violet
  • red
  • orange
  • yellow

  • 6. 
    A double convex air bubble in water behaves as:

  • Convergent lens
  • divergent lens
  • plane slab
  • concave mirror
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