Question

what is a focal length​

Answer 1

Answer:

The focal length of an optical system is a measure of how strongly the system converges or diverges light; it is the inverse of the system's optical power. A positive focal length indicates that a system converges light, while a negative focal length indicates that the system diverges light.

Answer 2

Explanation:

The focal length of an optical system is a measure of how strongly the system converges or diverges light; it is the inverse of the system's optical power.