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Wave Optics — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsWave Optics1 Mark
Question
For question two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true but R is NOT the correct explanation of A.
  3. A is true but R is false.
  4. A is false and R is also false.
Assertion (A): Light added to light can produce darkness.
Reason (R): The destructive interference of two coherent light sources may give dark fringe.
✓

Answer

  1. Both A and R are true and R is the correct explanation of A.
Explanation:

When light waves from two coherent sources superimpose at any particular point, crest of one wave falls on trough of the other and trough falls on the crest, the amplitude of the resultant wave is zero. Hence resultant intensity is zero. This is the phenomenon of destructive interference. Thus destructive interference produces darkness.

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