An object 50 cm tall is placed on the principal axis of a convex lens. Its 20 cm tall image is armed on the screen placed at a distance of 10 cm from the lens. Calculate the focal length of the lens.

A magnifying lens has a focal length of 100 mm. An object whose size is 16 mm is placed at some distance from the lens so that an image is formed at a distance of 30 cm in front of the lens.

(a) What is the distance between the object and the lens?

(b) Where should the object is placed if the image is to form at infinity?

A lens forms a real image 3 cm high of an object 1 cm high. If the separation of object and image is 15 cm, find the focal length of the lens.

If the image formed by a lens is always diminished and erect, what is the nature of the lens?

Copy and complete the diagram below to show what happens to the rays of light when they pass through the concave lens: