Objectives To demonstrate the formation of images from convex and concave lenses. To identify the type of image formed by convex and concave lenses. To identify the type of image formed by concave mirror.

Key Terms 1.Converging (or Convex lens): lens in which light rays that enter it parallel converge into a single point on the opposite side. 2.Diverging (or Concave lens): lens that causes light rays to bend away from its optical axis. 3.Focal Point F: for a converging lens or mirror, the point at which converging light rays cross; for a diverging lens or mirror, the point from which diverging light rays appear to originate 4.Focal length f: distance along the optical axis from the focal point to the Lens (or Mirror) that focuses the light rays 5.Object distance d0: distance between the object and lens (or mirror). 6.Image distance di: distance between the image formed and lens (or mirror). 7.Magnification m=h_i/h_0 =-d_i/d_0 . If m > 1, then image is enlarged; if m

Convex lens 1.Open https://phet.colorado.edu/sims/html/geometric-optics/latest/geometric-optics_en.html 2.Take some time to play with the simulation to get familiar with how it works. 3.Maximize your screen.

Pencil Index of Refraction Diameter O Rays Radius of Curvature Focal Points Marginal 80 cm 1.50 D 80 cm Virtual Image Principal O Labels O Many ) Second Point . O None Geometric Optics A PhET : Lens Mirror- > C D A phetcolorado.edu/sims/html/geometric-optics/latest/geometric-optics_en.html Update : Pencil Rays Radius of Curvature Index of Refraction Diameter Focal Points & O O Marginal Principal 80 cm 1.50 80 cm Virtual Image O Labels O Many Second Point . None Geometric Optics PhET : Lens