Question

The final image in an astronomical telescope is
A. Real and erect
B. Virtual and inverted
C. Real and inverted
D. Virtual and erect

Answer 1

Hint: In this question you have to take a conceptual approach. In an astronomical telescope there are two main convex lenses; one of the larger lenses is called an objective lens and the smaller lens which is used for viewing is called an eyepiece lens. Use this information to determine the nature of the final image formed in an astronomical telescope.

Complete Step-by-Step solution:
An astronomical telescope is an optical instrument which is used to see the magnified image of distant heavenly bodies. Since the focal length of astronomical scope is small due to which the final image formed by an astronomical telescope is always virtual, inverted and magnified.

Note: The objectives, which forms the image of the object that is far from us at its focal length,
And the eyepiece, which acts as a simple magnifier with which to view the image formed by the objective. Its length is equal to the sum of the focal lengths of the objectives and eyepiece, and its angular magnification is $\dfrac{{ - {f_o}}}{{{f_e}}}$, giving an inverted image. The focal length of the objective lens of an astronomical telescope is large as compared to the focal length${f_e}$of the eyepiece. And the aperture of the objective lens O is large as compared to that of eyepiece, so that it can receive more light from the distant object and forms a bright image of the object that is far from us. Thus, the final image formed by an astronomical telescope is always virtual, inverted and magnified.