Answer
A telescope is supposed to magnify objects, so its angular magnification should be greater than 1. Since magnification is $-\frac{fo}{fe}$, the eyepiece should have a shorter focal length than the objective lens. So we should use the lens with shorter focal length as the eyepiece and the other lens as the objective.
Work Step by Step
A telescope is supposed to magnify objects, so its angular magnification should be greater than 1. Since magnification is $-\frac{fo}{fe}$, the eyepiece should have a shorter focal length than the objective lens. So we should use the lens with shorter focal length as the eyepiece and the other lens as the objective.
