# The focal length of the first converging lens is 30 cm, and the focal length of the second

October 3, 2021 | education

| **The focal length of the first converging lens is 30 cm, and the focal length of the second converging lens is 10 cm. The optical power of which lens is greater? How many times?**

To find the ratio of the optical powers of a given collecting lens, we will use the formula: k = D2 / D1 = (1 / F2) / (1 / F1) = F1 / F2.

Values of variables: F1 – focal length of the first given collecting lens (F1 = 30 cm); F2 is the focal length of the second converging lens (F2 = 10 cm).

Calculation: k = F1 / F2 = 30/10 = 3 p.

Answer: The optical power of the second collecting lens is 3 times greater.

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