A concave lens produces an image 20 cm from the lens of an object placed 30 cm from the lens. The focal length of the lens is:

A small object is placed 150 mm away from a diverging lens of focal length 100 mm.

(i) Copy the figure below and draw rays to show how an image is formed by the lens.

(ii) Calculate the distance of the image from the lens by using the lens formula.

The diverging lens in part (a) is replaced by a converging lens also of focal length 100 mm. The object remains in the same position and an image is formed by the converging lens. Compare two properties of this image with those of the image formed by the diverging lens in part (a).

Only one of the following applies to a concave lens. This is:

The magnification produced by a spherical mirror and a spherical lens is + 0.8.