Question

The focal lengths of the eyepiece and the objective of an astronomical telescope are 2cm and 100cm respectively. The magnifying power of the telescope for normal adjustment and the length of the telescope are respectively:

• A. $-50,100cm$
• B. $-50,102cm$
• C. $-40,100cm$
• D. $-50,104cm$

Answer 1

Answer: (B)

$-50,102cm$

$f_e=2cm$

$f_o=100cm$

$M=?$

$L=?$

$M=\frac{100}{2}=-50=\frac{f_o}{f_e}$

$L=f_o+f_e=102cm$