A department store sells an "astronomical telescope" with an objective lens of 30 cm focal length and an eyepiece lens of focal length 5 mm.What is the magnifying power of this telescope?
A) 150×
B) 6×
C) 15×
D) 60×

Question

Quizplus · Accepted Answer

The magnifying power of the telescope is given by the formula M = -fo/fe, where fo is the focal length of the objective lens and fe is the focal length of the eyepiece lens. Substituting the given values, we get
M = -30/0.005 = -6000
Note that the magnifying power is negative, indicating that the image is inverted. Taking the absolute value of this result, we get
|M| = 6000
Therefore, the magnifying power of the telescope is 60×.

A Department Store Sells an "Astronomical Telescope" with an Objective