JEE Main 2026 Physics question
A telescope with objective diameter R is used to observe a distant star emitting light of wavelength 500 nm, at a resolution of 5 × 10⁻⁷ radian. The value of R is cm.
Answer: (B)
Solution
θ = 1.22λ/R gives R = 1.22 × 500×10⁻⁹/(5×10⁻⁷) = 1.22 m = 122 cm.