Answer: Disappears and single diffraction pattern remains.
- A Disappears and single diffraction pattern remains
- B Doubles in fringe width while interference continues normally
- C Shifts entirely to one side of the screen but persists
- D Remains exactly the same as with both slits open
Correct answer: A. Disappears and single diffraction pattern remains
Explanation: When one slit is covered, there is no two-source interference. Only a single-slit diffraction pattern remains. The sharp interference fringes disappear.
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.