Experiment 13: Focal Length and Magnification of a Thin Lens Pre-lab (Advanced study ) 1. Use a ray diagram and indicate the position and size of an object that is at 3f from a convex lens. Is the image real or virtual? Explain your answer. 2. Explain the nature image formed by concave lenses. 3. What is the nature of images formed by surveillance mirrors at department stores? Are these mirrors the same as the mirrors we use in our dressing room? Explain.\f\f\f