JEE Main 2026 Physics question
Some distant star is to be observed by some telescope of diameter of objective lens a, at an angular resolution of 3.0×10⁻⁷ radian. If the wavelength of light from the star reaching the telescope is 500 nm, the minimum diameter of the objective lens of the telescope is cm. (nearest integer)
Answer: 203
Solution
θ=1.22λ/a gives a=1.22×500×10⁻⁹/(3.0×10⁻⁷)=2.033 m≈203 cm.