An astronomical telescope has an objective of diameter 20 cm with a focal length of 180 cm.The telescope is used with an eyepiece of focal length 30 mm.What is the angular magnification of this telescope?
A) 360 x
B) 60 x
C) 540 x
D) 6 x
E) 180 x

Question

Quizplus · Accepted Answer

Angular magnification, M = (focal length of objective)/(focal length of eyepiece) 
= (180 cm)/(3 cm) 
= 60 
Therefore, the angular magnification of the telescope is 60x.

An Astronomical Telescope Has an Objective of Diameter 20 Cm