(a) A giant refracting telescope at an observatory has an objective lens of focal length 15m. If an eyepiece of focal length 1.0cm is used, what is the angular magnification of the telescope? (b) If this telescope is used to view the moon, what is the diameter of the image of the moon formed by the objective lens? The diameter of the moon is 10^{6} m, and the radius of lunar orbit is 10^{8}$$ m.
The angular magnification of the telescope is 1500.
The diameter of the image of the moon formed by the objective lens is 13.74 cm (or 0.137 m).
Explanation
Part (a) uses the standard telescope magnification formula m = f₀/fₑ. Part (b) requires understanding that for distant objects, the image is formed at the focal plane of the objective lens. The angle subtended by the moon at the objective equals the angle subtended by the image at the objective, allowing us to calculate the image size using similar triangles.