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The minimum angular magnification of an astronomical telescope is 10 X. The focal length of objective.

aditya kashyap , 11 Years ago
Grade upto college level
anser 1 Answers
Saurabh Koranglekar

Last Activity: 5 Years ago

Given:
Minimum angular magnification of an astronomical telescope, M_min = 10X

For an astronomical telescope in normal adjustment (final image at infinity), the angular magnification is given by:

M = f_o / f_e

where:

f_o = focal length of the objective
f_e = focal length of the eyepiece
Since the problem gives M_min, it implies that the telescope has been adjusted for minimum magnification. This occurs when the telescope is in normal adjustment.

Thus, we write:

10 = f_o / f_e

To determine f_o, we need f_e, but it is not given in the problem. However, the minimum magnification of an astronomical telescope is approximately given by:

M_min ≈ D / f_o

where D is the least distance of distinct vision, generally taken as 25 cm.

Rearranging for f_o:

f_o = D / M_min
f_o = 25 cm / 10
f_o = 2.5 cm

Therefore, the focal length of the objective is 2.5 cm.

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