Browse by Stream
QnA
Home
QnA
Go To Your Study Dashboard

Get Answers to all your Questions

header-bg qa
  • Home
  • NCERT
  • An astronomical refractive telescope has an objective of focal length 20m and an eyepiece of focal length 2cm. A. The length of the telescope tube is 20.02m.

An astronomical refractive telescope has an objective of focal length 20m and an eyepiece of focal length of 2cm.
A. The length of the telescope tube is 20.02m.
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.

Answers (1)

Hence, the correct answer is an option (a,b, and c).

Explanation:-

 

  • Use to see heavenly bodies.
  • f_{objective}>f_{eye\; lens} and d_{objective}>d_{eye\; lens}
  • The intermediate image is real, inverted, and small.
  • The final image is virtual, inverte,d and small.

 

  • Magnification:
  • m_{D}=-\frac{f_{0}}{f_{e}}\left ( 1+\frac{f_{e}}{D} \right ) and  m_{\infty }=-\frac{f_{0}}{f_{e}}
  • Length :
  • L_{D}=f_{0}+u_{e}=f_{0}+\frac{f_{e}D}{f_{e}+D} and  L_{\infty }=f_{0}+f_{e}

The length of the telescope tube is

f_{0}+f_{e}=20+(0.02)=20.02\; m

Also,

m=\frac{20}{0.02}=1000

Also, the image formed is inverted.

Posted by

infoexpert23

View full answer

Similar Questions

Latest Question