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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): Interference obeys the law of conservation of energy.
Reason (R): The energy is redistributed in case of interference.
✓

Answer

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

Explanation:

ln case of interference, intensity of maxima is $\text{I}_\text{max}=\Big(\sqrt{\text{I}_\text{a}}+\sqrt{\text{I}_\text{b}}\Big)^2$ and intensity of minima is $\text{I}_\text{min}=\Big(\sqrt{\text{I}_\text{a}}-\sqrt{\text{I}_\text{b}}\Big)^2$. Thus, whatever energy disappears at the minimum is actually appearing at the maximum. So, the law of conservation of energy holds good in the phenomenon of interference because in interference energy is neither created nor destroyed but is redistributed.

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