Question

WHAT IS A FOCAL LENGHT

Answer 1

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This font is used to denote single letter notations in 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

Focal length, usually represented in millimeters (mm), is the basic description of a photographic lens. ... Lens focal length tells us the angle of view—how much of the scene will be captured—and the magnification—how large individual elements will be.

Answer 2

Answer:

The focal length is the distance from the center of the lens to the principal foci (or focal points) of the lens. For a converging lens (for example a convex lens), the focal length is positive, and is the distance at which a beam of collimated light will be focused to a single spot.