Question

The magnifying power of a telescope with tube length 60 cm is 5. What is the focal length of its eye piece ?

• A. $30cm$
• B. $40cm$
• C. $10cm$
• D. 20 cm

Answer 1

Answer: (C)

$L=f_0+f_e-60cm$
$M=\frac{f_0}{f_e}=5$
$\Rightarrow f_0=5f_e$
$\therefore 6f_e=60cm$
$f_e=10cm$