Question

The focal length of the lens of a simple camera is 40.0 mm. how far must the lens be moved to change the focus of the camera from a person 25 m away to one that is 4.0 m away?

Answer 1

.05 cm far must the lens be moved to change the focus of the camera from a person 25 m away to one that is 4.0 m away

The focal length of a thin lens in air is the separation between its major foci, also known as focal points, and its center. The focal length is the distance at which a beam of collimated light will be concentrated to a single spot for a converging lens (for instance, a convex lens).

If v is the image distance in the first scenario

1 / v - 1 / -25 = 1 / .05

1 / v = 1 / .05 - 1 / 25

= 20 - .04 = 19.96

v = .0501 m = 5.01 cm

The second instance

u = 4 ,

1 / v - 1 / - 4 = 1 / .05

1 / v = 20 - 1 / 4 = 19.75

v = .0506 = 5.06 cm

Therefore, the lens must be advanced by 5.06 - 5.01 =.05 cm.

Learn more about  lens here brainly.com/question/17086993

#SPJ4.