Question

The length of a telescope is 36 cm The focal lengths of its lenses can be

• A. 30 cm , 6 cm
• B. -30 cm ,-6 cm
• C. 30 cm ,-6 cm
• D. -30 cm , 6 cm

Answer 1

Answer: (A)

Length of a telescope, $L=f_o+f_e=36cm$ and both the lenses are convex.
$\therefore f_o=30cm,f_e=6cm$