Physics II Lab Report #11

Lab #_11_ Group: 11 Title: Mirrors, Lenses, Telescopes Preliminary Question Answers: 1) The image projected on a movie screen is real since the light beam from an object’s point meets and can be projected onto the screen which creates a real image. The image of yourself seen in a bathroom mirror is virtual since the light beams from an object’s point appear where the light doesn’t pass through. 2) The differences between the image of your face seen on the convex and concave sides of a spoon are that on the convex side of the spoon, the image is smaller and upright while on the concave side of the spoon, the image is larger and if you move away from the spoon, the image can’t be seen. 3) The images formed on each side of the spoon are found in behind the spoon for the convex side while the image is formed in front of the spoon for the concave side. Analysis: 1) When the object and image distances for the mirror are equal, the theoretical magnification is 1 which is the same value entered in the data table. 2) The relationship between f and r for the mirror is that r = 2f. 3) The graph is shown below under graphs. 4) The slope and the intercept are shown in the data table. The focal length obtained from the intercept is 1/0.0933 = 10.7 cm. 5) The focal length obtained from the intercept is around the same as the focal length obtained from the distant object with the intercept being 10.7 cm and the distant object being 10 cm.

6) The difference between the incident rays approaching each lens is that in lens A the incident rays converge from a real object while in lens C the incident rays diverge from a virtual object. 7) The difference between the rays leaving lens A and those leaving the plane mirror in that figure is that the rays leaving lens A are converging from a real object whereas the rays leaving the plane mirror in that figure are diverging from a virtual object. 8) The measured angular magnification of the telescope is the same value as the theoretical prediction which is 4. Data Tables: Table 1 Mirror Radius of curvature of mirror = 20 cm Focal length of mirror = 10 cm Magnification = 1 Table 2 Converging Lens Object distance, s (cm) Image distance, s’ (cm) 1/s ( cm ) − 1 1/s’ ( cm ) − 1 20 21 0.05 0.04 25 19.5 0.04 0.051 30 17 0.033 0.059 35 16 0.029 0.063 40 15 0.025 0.066 Slope of graph = -1.0601 Intercept of graph = 0.0933 Focal length from intercept = 10.7 cm Focal length from distant object = 10 cm Table 3 Diverging Lens Image distance for lens A = 17 cm Object distance for lens C = 10 cm Image distance for lens C = 7 cm Focal length of lens C = 4.2 cm Table 4 Telescope Focal length of lens A = 40 cm Focal length for lens B = 10 cm Theoretical angular magnification = 4 Measured magnification = 4