Target Exam

CUET

Subject

Physics

Chapter

Ray Optics

Question:

If f1 = 12 cm, f2 = – 18 cm find the maximum focal length of the combination?

Options:

36 cm

34 cm

32 cm

30 cm

Correct Answer:

36 cm

Explanation:

$\frac{1}{F} = \frac{1}{f_1} + \frac{1}{f_2} = \frac{1}{12} + \frac{1}{-18} = \frac{3-2}{36}$

$\Rightarrow F = 36cm$