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

An astronomical refractive telescope has an objective of focal length

1.	An astronomical refractive telescope has an objective of focal length 20 m and an eyepiece of focal length 2 cm.
Answer» The length of the telescope tube is 20.02m. 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. Solution :Tube length of telescope, `f_0 + f_e = 20 + (0.02) = 20.02 m` Hence option (A) is correct. Magnification OBTAINED by telescope, `m=(f_0)/(f_e)=(20)/(0.02)=1000` Hence option (B) is ALSO correct. In case of telescope, final image is inverted w.r object. Hence option (C) is also correct.

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

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