A research observatory plans to design a Newtonian reflecting telescope for deep-sky…
PHYSICS · Multi-part · CBSE · Physics · Ray Optics and Optical Instruments · Ray Optics and Optical Instruments
Problem
A research observatory plans to design a Newtonian reflecting telescope for deep-sky observations.
(i) The required angular magnification is 100 when an eyepiece of focal length 2.5cm is used in normal adjustment. Calculate the focal length that the primary mirror should have.
(ii) If the primary mirror has a diameter of 0.25m, determine the ratio of the telescope’s light-gathering power to that of the human eye, taking the average pupil diameter as 6mm.
(iii) Without further calculation, explain why increasing the diameter of the primary mirror improves both the brightness and the resolution of the observed image even though the magnification depends only on focal lengths.