Question

An object is clearly seen through an astronomical telescope of length 50 cm. The focal lengths of its objective and eye-piece respectively can be ______.

Options

• 5 cm and 45 cm

• - 45 cm and - 5 cm

• 45 cm and - 5 cm

• 45 cm and 5 cm

Answer 1

An object is clearly seen through an astronomical telescope of length 50 cm. The focal lengths of its objective and eye-piece respectively can be 45 cm and 5 cm.

Explanation:

An astronomical telescope's objective and eyepiece are made up of convex lenses with a positive focal length. In addition, the astronomical telescope's objective has a big aperture and focal length. As a result, the objective and eyepiece focal lengths can be 45 cm and 5 cm, respectively.