Answer: The diameter of the objective lens.
- A The diameter of the objective lens
- B The focal length of the eyepiece
- C The magnification
- D The colour of light
Correct answer: A. The diameter of the objective lens
Explanation: Resolving power limit θ_min = 1.22λ/D. A larger objective diameter D allows resolution of closer objects. Hence larger telescopes resolve finer details.
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.