Answer
A refracting telescope with a large angular magnification requires a longer focal length objective lens in order to produce a larger magnified image. This means that the telescope tube must be longer in order to accommodate the longer lens. In contrast, a telescope with a smaller angular magnification can use a shorter focal length objective lens and therefore have a shorter telescope tube. This is because the size of the image is inversely proportional to the focal length of the lens. A longer focal length lens forms a smaller image, thus the telescope must be longer.
Work Step by Step
A refracting telescope with a large angular magnification requires a longer focal length objective lens in order to produce a larger magnified image. This means that the telescope tube must be longer in order to accommodate the longer lens. In contrast, a telescope with a smaller angular magnification can use a shorter focal length objective lens and therefore have a shorter telescope tube. This is because the size of the image is inversely proportional to the focal length of the lens. A longer focal length lens forms a smaller image, thus the telescope must be longer.
