An astronomical telescope is to be designed to have a magnifying power of 50 in normal
adjustment. If the length of the tube is 102 cm, find the powers of the objective and the eyepiece.
Given data -
Magnifying power of the astronomical telescope, m = 50
Length of the tube, L = 102 cm
Let f0 and fe, be the focal length of objective and eye piece
Then using the formula for magnification, m
Substituting the values-
Also
Substituting (2) in (1)
And, substituting the value in (1)
Hence, the power, which is reciprocal of focal length becomes-
For objective lens -
And,
For eye piece lens