Answer: The slit with the mica sheet.
- A The slit with the mica sheet
- B The other slit
- C Does not shift
- D Depends on wavelength
Correct answer: A. The slit with the mica sheet
Explanation: The mica sheet increases the optical path on that side. The central fringe (equal optical path) shifts toward the side with the sheet to compensate.
Two coherent slits S₁ and S₂ act as secondary sources; at each point on the screen, the path difference between light from S₁ and S₂ determines whether the waves arrive in phase (bright fringe) or out of phase (dark fringe), producing the characteristic alternating fringe pattern.
Concept context
Huygens principle, Young's double slit, diffraction, polarization. Essential for JEE.