Question

For a telescope having $f_{o}$ as the focal length of the objective and $f_{e}$ as the focal length of the eyepiece, the length of the telescope tube is

• A. $f_{e}$
• B. $f_{o}-f_{e}$
• C. $f_{o}$
• D. $f_{o} +f_{e}$

Answer 1

Answer: (D)

Given $f_{o}=f_{o}$ and $u_{e}=f_{o}$
We know for length of the telescope tube
$L=f_{o}+u_{o}$
$L=f_{o}+f_{e}$