Q137 / 180 · AIIMS 2019 (26 May) · Physics
A telescope, whose objective lens has an aperture of $1 \mathrm{~mm}$ for the wavelength of light $500 Å$, then limiting resolving power of the telescope is
- A$2.1 \times 10^{-5} \mathrm{rad}$
- B$4.1 \times 10^{-5} \mathrm{rad}$
- C$5.1 \times 10^{-5} \mathrm{rad}$
- Correct answerD$6.1 \times 10^{-5} \mathrm{rad}$
Solution
Given:
Aperture of objective lens $(a)=1 \mathrm{~mm}=1 \times 10^{-3} \mathrm{~m}$ Wavelength of light $(\lambda)=500 Å=500 \times 10^{-10} \mathrm{~m}$ Limiting resolving power of telescope,
$d \theta=\frac{1.22 \lambda}{a}=\frac{1.22 \times 500 \times 10^{-10}}{1 \times 10^{-3}}=6.1 \times 10^{-5} \mathrm{rad}$
Hence, the correct answer is option: 'D'.