The magnification of the telescope image is

(focal length of the objective) divided by (focal length of the eyepiece).

The focal length of the objective is fixed.
Decreasing the focal length of the eyepiece increases the magnification of the image.
(But it also makes the image dimmer.)

It is called the focal length. It is equal to 1/2 times r, and is positive on concave mirrors and negative on convex mirrors.

The focal length of a telescope is directly related to the magnification in that the longer the focal length, the more magnification you get from the telsceope. How the focal length of a telescope relates to the length of the telescope itself depends on the design of the telescope. In a refracting telescope, the focal length is approximately the length of the telescope. In a reflecting telescope, the focal length is roughly two time the length of the telescope.

The magnifying power of a telescope is the focal length of the scope in millimeters, divided by the focal length of the eyepiece in millimeters. Focal length of scope: 225cm=2250mm Focal length of eyepiece: 7.5mm 2250/7.5= 300X

The magnification of the telescope image is

(focal length of the objective) divided by (focal length of the eyepiece).

The focal length of the objective is fixed.
Decreasing the focal length of the eyepiece increases the magnification of the image.
(But it also makes the image dimmer.)