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Question
An astronomical refractive telescope has an objective of focal length 20 m and an eyepiece of focal length 2 cm.
- The length of the telescope tube is 20.02 m.
- The magnification is 1000.
- The image formed is inverted.
- An objective of a larger aperture will increase the brightness and reduce chromatic aberration of the image.
Options
a, b and c
a, c and d
b, c and d
c and d
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Solution
a, b and c
Explanation:
The length of the telescope
L = f0 + fe = 20 + 00.02 = 20.02 m
And `m = f_0/f_e = (20 m)/(0.02 m) = 2000/2` = 1000
The final image formed in the telescope (Refracting) is inverted, virtual and smaller than an object.
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