Question

The refracting telescope at Yerkes Observatory has a 1.00m diameter objective lens of focal length 20.0m. Assume it is used with an eyepiece of focal length 2.50cm.

(a) Determine the magnification of Mars as seen through this telescope.

Answer 1

By the definition of the angular magnification, we get:

$$m=-\dfrac{f_o}{f_e}=-\dfrac{20.0\ m}{0.025\ m}=-800.$$

The sign minus means that the image is inverted.