Answer: sinθ = λ/a (a = slit width).
- A sinθ = λ/a (a = slit width)
- B sinθ = λ/2a, half the correct angular condition
- C sinθ = 2λ/a, double the correct angular condition
- D sinθ = a/λ, the reciprocal of the correct ratio
Correct answer: A. sinθ = λ/a (a = slit width)
Explanation: For single slit diffraction, first minimum: a sinθ = λ, so sinθ = λ/a. The central maximum has angular width 2λ/a.
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.