If the tube length of astronomical teles

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Target Exam

CUET

Subject

Physics

Chapter

Ray Optics

Question:

If the tube length of astronomical telescope is 105 cm and magnifying power is 20 for normal setting, calculate the focal length of the objective

Options:

100 cm

10 cm

20 cm

25 cm

Correct Answer:

100 cm

Explanation:

$L=f_0+f_e$ = 105 cm and M = $\frac{f_0}{f_e}$ = 20

$\Rightarrow f_0$ = 100 cm and $f_e$ = 5 cm