Question

A telescope has an objective lens of 10 cm diameter and is situated at a distance of $1km$ for two objects. The minimum distance between these two objects, which can be resolved by the telesope, when the mean wavelength of light is 5000Å is of the order of

• A. 5 cm
• B. 0.5 mm
• C. 5 m
• D. 5 mm

Answer 1

Answer: (D)

5 mm

Resolution power $=\frac{d\lambda }{D}=\frac{1000\times 5000\times {10}^{-10}}{10\times {10}^{-2}}=5mm$