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An astronomical refractive telescope has...

An astronomical refractive telescope has an objective of focal length 20 m and an eyepiece of focal length 2 cm. Then

A

The length of the telescope tube is 20.02 m.

B

The magnification is 1000.

C

The image formed is inverted.

D

An objective of a larger aperture will increase the brightness and reduce chromatic aberration of the image.

Text Solution

Verified by Experts

The correct Answer is:
A, B, C
Given, focal length of objective, `f_(0)=20cm`
Focal length of eye piece, `f_(e)=2cm=0.02m`
For normal adjustment, the length of the telescope is
`L=f_(o)+f_(e)=20m+0.02m`
`=20.02m`
`"Magnification, m"=(f_(0))/(f_(e))=(20m)/(0.02m)=1000`
Also, the image formed by the astronomical telescope is inverted.
The correct options are (a), (b), and (c).
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