I need help finding the answer to this question for astronomy.

Question

To increase the magnification of an object through a telescope which of the following would you do or request?

 A. adjust the collimation of the telescope

 

 B. Get an eye piece with a shorter focal length

 

 C.  get an eye piece with a longer focal length

 

Answer 1

Answer C

Because magnification = focal length of the objective / focal length of the eyepiece.

Dividing by a smaller number (shorter eyepiece focal length) gives a larger answer (magnification).