An object is placed 10 cm in front of a lens. The image formed is real, inverted and of same size as the object. What is the focal length and nature of the lens?

- Identify the nature of the lens based on the image characteristics (real, inverted implies converging). - Use the magnification information (same size implies |m|=1) and image type (inverted implies m=-1) to relate object and image distances (v=u). - Apply the lens formula (1/f = 1/v - 1/u) with appropriate sign conventions or use the special case rule for an image of the same size formed by a converging lens (object at 2f). - Determine the sign of the focal length to confirm the nature of the lens (positive f for converging).