Question

What does focal length mean?

Answer 1

Answer:

The distance between the centre of a lens or curved mirror and its focus is referred as focal length.

Explanation:

POINTS TO NOTE:

• The focal length of a lens is an indicator of the distance from the subject
• The focal length of the average, healthy, adult human eye at near-point is about 18.5 mm.

• To measure the focal length of a converging (convex) lens. Using the formula: 1/u + 1/v = 1/f, the focal length f of the lens can be found.
• The focal length of the human eye is the distance between the lens and the retina when an object is in focus

HOPE HELPED

Answer 2

Answer:

The distance between the optical centre and principal focus of the lens.