Answer: The slit width is halved.
- A The slit width is halved
- B The wavelength is halved
- C The screen distance is halved
- D The slit width is doubled
Correct answer: A. The slit width is halved
Explanation: Angular half-width of central max = λ/a. Full angular width = 2λ/a. Halving the slit width a doubles the angular width.
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.