Objectives: The purpose of this experiment is to investigate properties of thin lenses and image formation, We will use simulation software to study focal length, object and image distances, and the magnification of thin lenses. Equipment: . Computer . Scientific Calculator . Ruler with cm scale . Lenses and Mirrors Simulation Software (The Physics Classroom) Theory: . For thin lenses, the relationship between the focal length f, the distance between the object and the lens do, and the distance between the image and the lens di, is similar to spherical mirrors and is given by: d d, The object distance d. is positive if the object is located in front of the lens (real), and negative if it is located behind the lens (virtual). The image distances d; is positive if the image is located in behind of the lens (real), and negative if it is located in front of the lens (virtual). Double Plano- Convex Double Plano- Concave convex convex meniscus concave concave meniscus Converging lenses Diverging lenses. For thin lenses spherical mirrors, the focal length f is given by the lens maker's equation: = (1-1) R R, Where a is the index of refraction of the lens material, R, is the radius of curvature of the first lens surface, and Ra is the radius of curvature of the second lens surface. The focal length fis positive for converging lenses and negative for diverging lenses. The radii of curvature R, and Ry are positive if they are on the outgoing side of the lens and negative if they are on the opposite side. . If the object is very far from the lens, then: d ->0 - d = f . The magnification M of a lens is defined as the ratio of image size h, to object size h., and it can be determined from: M h If the image is upright, then M is positive, and if the image is inverted, then M is negative. . A virtual image cannot be viewed on a screen. It forms where the backward extensions of diverging rays cross. You can see a virtual image by looking at it through a lens or mirror. . Principle rays are convenient to use in ray diagrams to trace the path of the rays and determine the formation of the image. Three principle rays for concaving and diverging lenses are shown: Converging lenses object Diverging lenses\fLenses and Mirrors LENS -H Part A - Converging Lens with f = 18.8 cm: . Open the Lenses and Mirrors Simulation Software: https://www.physicsclassroom.com/Physics-Interactives/Refraction-and-Lenses/Optics- Bench/Optics-Bench-Refraction-Interactive >Click the icon in the top-left corner or drag the icon in the lower- right corner of the simulation fame to maximize the simulation. In the simulator leave all rays on "Ray 1, 2, 3 ON" (bottom left) > The values of the focal length (f), object distance (do), object height (h,), image distance (d,), and image height (h,) are given on the bottom right. Note: The given values in the simulation are all "absolute values". When recording the values in the data tables be sure to include the correct signs, as discussed in the theory. . On the top right, select "Converging" to change lens to a Converging lens. . In the simulator set: Absolute value of "Focal Length" = 18.8 cm, and "height" = 19.0 cm, shown in the above figure. . Record the accepted focal length face value in the below table. . Position the object (candle) so it is located at the object distance do = 70.0 em to left of the lens. . Record the object distance (d, ), object height (h.). image distance (d;), and image height (he) in the below table.. Repeat the above procedure for the rest of the object distances do given in the below table for a total of 5 trials. Record the data in the below table. . Save a screenshot (screen capture) of the simulation showing the lens, object, and image for one of the trials to include in the graphs section of your report. Part B - Converging Lens with f = 22.8 cm: . In the simulator set: Absolute value of "Focal Length" = 28.8 em, and "height" = 19.0 cm, as shown in above figure. . On the top right, select "Converging" to change lens to a Converging lens. . Record the accepted focal length face value in the below table. . Repeat the procedure from Part A for the object distances given in the below table for a total of 5 trials . Record the object distance (do), object height (h. ), image distance (d,), and image height (h,) in the below table. . Save a screenshot (screen capture) of the simulation showing the lens, object, and image for one of the trials to include in the graphs section of your report. Part C - Diverging Lens with f = -22.8 em: . In the simulator set: Absolute value of "Focal Length" = 28.8 cm, and "height" = 19.0 cm, as shown in above figure. . On the top right, select "Diverging" to change lens to a Diverging lens. . Record the accepted focal length facc value in the below table. (Remember that for a diverging lens the focal length is negative.) . Repeat the procedure from Part A for the object distances given in the below table for a total of 5 trials . Record the object distance (d.), object height (h,), image distance (d,), and image height (h,) in the below table. . Save a screenshot (screen capture) of the simulation showing the lens, object, and image for one of the trials to include in the graphs section of your report.Analysis: . Part A - Converging Lens with f'= 18.8 cm: 1. For each of the trials, calculate the accepted value of the image distance d, using the lens equation given in the theory section, the given value of the object distance do, and the accepted value of the focal length face. Record values in the below table. 2. Remember to use the correct signs for all values when performing the calculations, as discussed in the theory section! 3. Compare the experimental and the accepted values of the image distance d, by calculating the % errors. Record values in the below table. 4. For each of the trials, calculate the experimental value of the magnification M from the measured ho and h, values, and the accepted value of the magnification M from the measured do and di values. Record values in the below table. 5. Compare the experimental and the accepted values of the magnification M by calculating the % error. Record values in the below table. 6. How do the values compare what factors do think may cause there to be a difference between these values? Discuss in your lab repot. 7. Based on your observations, describe the image position, size, and orientation for object distances: do > 2f, do = 2f. f 2f. do = 2f.f 2f. do = 2f f