Question

the focal length is represented by which number​

Answer 1

Explanation:

The symbol, f, represents the focal length. F/ number is a measure of the speed and clarity of the optical system. It is the ratio of the focal distance to the aperture size. Fast systems have small F/numbers such as F/1, F/2 or F/3.

Answer 2

Answer:-

Focal length is represented by the symbol 'f'.

Additional information:

Focal Length: It is the distance between the center of cutvature of a mirror or a lens at its focus.

Focal length tells us the angle of view.

It is determined by the index of refraction of different surfaces.

We can calculate focal length by this formula:

1/u + 1/v = 1/f, where u is the object distance v is the image distance and f is the focal length.