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JEE Main 2026 (4 Apr, Shift 1) · Resolving Power

Resolving Power question from JEE Main 2026 (4 Apr, Shift 1)

Q3JEE Main 2026 · 4 APR · SHIFT 1Easy

Resolving Power

A telescope with objective diameter RR is used to observe a distant star emitting light of wavelength 500 nm, at a resolution of 5×10−75 \times 10^{-7} radian. The value of RR is

______ cm.

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Answer: (b)

  1. θ=1.22λR⇒R=1.22λθ\theta = \dfrac{1.22\lambda}{R} \Rightarrow R = \dfrac{1.22\lambda}{\theta}.
  2. R=1.22×500×10−95×10−7=1.22R = \dfrac{1.22\times500\times10^{-9}}{5\times10^{-7}} = 1.22 m
  3. So the answer is (b) 122 cm.
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