The filament of a lamp is 80 cm from a screen and a converging lens forms an image of it on a screen, magnified three times. Find the distance of the lens from the filament and the focal length of the lens.

At what distance should an object be placed from a convex lens of focal length 12 cm to obtain an image at 24 cm from it on the other side? What will be the magnification produced in this case?

An object 3 cm tall is placed on the axis of a convex lens of focal length 5 cm at a distance of 10 m from the optical center of the lens. Find the nature, position and size of the image formed. Which case of image formation by convex lenses is illustrated by this example?

An erect image 2.0 cm high is formed 12 cm from a lens, the object being 0.5 cm high. Find the focal length of the lens.

A convex lens of focal length 0.10 misused to form a magnified image of an object of height 5 m placed at a distance of 0.08 m from the lens. Calculate the position, nature and size of the image.