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The figure shows a simple arrangement wh...

The figure shows a simple arrangement which works as an astronomical telescope. The arrangement consists of two convex lenses placed coaxially. The lens which faces a distant object is called the objective. It has a large aperture and a large focal length also. The second lens is closed to the observers eyes. It is called the eyepiece. It has a smaller aperture as compared to the objective. Its focal length is also small in comparison to objective.

The objective forms a real image of a distant object. This image acts as the object for the eyepiece. The eye-piece may form its image at a large distance `(oo)` or at least distance of distinct vision (D = 25 cm). The magnifying power of the telescope is the ratio `(-beta)/(alpha)`. Maximum angular magnification is produced when the final image is at the least distance of distinct vision.
A telescope has an objective of focal length 50 cm and an eye-piece of focal length 5 cm. The least distance of distinct vision is 25 cm. The telescope is adjusted for distinct vision and it is focussed on an object 200 cm away. The length of the telescope is

A

`L = f_(0) + f_(e)`

B

`L lt f_(0) + f_(e)`

C

`L gt f_(0) + f_(e)`

D

`L = f_(0) - f_(e)`

Text Solution

Verified by Experts

The correct Answer is:
B
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