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Question 20230
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Electromagnetic Waves and Wave Optics: Diffraction — Resolving Power of Telescope MCQ

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Diffraction — Resolving Power of TelescopeHardQuestion 20230

Question

A telescope with objective diameter 5 cm is used with λ = 550 nm. Minimum angular separation (Rayleigh) it can resolve is:
  1. A
    13.4 μrad
    Correct
  2. B
    1.34 μrad
  3. C
    134 μrad
  4. D
    0.134 μrad

Correct answer

13.4 μrad

Explanation

θ = 1.22λ/D = 1.22 × 550×10⁻⁹/0.05 = 1.22 × 1.1×10⁻⁵ = 1.342×10⁻⁵ rad ≈ 13.4 μrad.

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