After dropping a box containing converging lenses, an explorer needs to determine tAfter dropping a box containing converging lenses, an explorer needs to determine the focal length of each lens. He places a bright flashlight 0.6 m from the lens such that the light shines through the lens. The image of the filament in the bulb is brought to a sharp focus on a sheet of paper held 0.2 m on the opposite side of the lens from the flashlight.

What is the focal length?

+ 0.6 m

- 0.2 m

+0.15 m

- 0.15 m