Data Sheet online (M2. formtion of images by a converging lens)(3)

(PHY 156) This datasheet is due May.15 __________________________________________________________________ Data Sheet (M2. Formation of images by a converging lens ) - Your Name: Harrison Dhouib Reading assignment https://openstax.org/books/college-physics/pages/25-6-image-formation-by-lenses PHY 156 manual ‘LABWORK 14’ ( Formation of an image by a thin convex lens ) Video clips for vlab https://www.youtube.com/watch?v=Cqovl05UUdY (Lecture and Simple experiment) https://www.youtube.com/watch?v=SouVpSqJSlE (How to use the simulator) https://www.youtube.com/watch?v=lBKGP6Fh9vs (How to use the simulator; real and virtual images) Simulator for formation of an image To find the simulators access the links (Simulator 1 ) https://phet.colorado.edu/sims/geometric-optics/geometric-optics_en.html The main formula: - The Lens equation for a lens whose focal length is f reads 1 d o + 1 d i = 1 f Eq.1 where d o is the object distance and d i the image distance. Objective: - You examine the formation of images by a converging lens using Simulator 1 . You test the lens equation by forming a real images ( Part 1 ) and virtual images ( Part 2 ). Task: - (1) Fill out the tables (on pages 3 through 4) with your data that you got from the simulation and (2) answer the post-virtual-lab questions on page 5. When you fill out the table, check sample calculations. Page 1

(PHY 156) This datasheet is due May.15 __________________________________________________________________ Procedure: Access the web link for Simulator 1 . Part 0 Getting familiar with the law of reflection . (Play with the simulator.) 1. On the simulator a pensile (‘object’) emits laser beams from the left side of the simulator and the beams merge at a point on the right side. Drag the object (or the sign ‘move here’), then observe how the location of merging point changes. 2. ( Laser beams ) You can choose ‘Marginal rays’, ‘Principal rays’ or ‘Many rays’. The Marginal Rays pass through only the edges and center of the lens. The Principal rays pass through the center of lens and focal point. The Many rays are the most realistic imitation of actual laser beams here and radiate in all the direction from the object. The Principal rays are a ‘text-book-like’ laser beams; they show only physically important rays. We use the Principal rays . Also, you can add a second light source by clicking on ‘2 nd Point’ on the top panel. You also can change the shape of the object by clicking on ‘Change Object’ on the top panel. 3. ( Objects and screen ) For this vlab, we need to find out distances among focal point, screen and object. Click on ‘ Ruler ’ then you can use a ruler; you can move it around but can not rotate it. Also, click on ‘ Screen ’, then you can use a stand light as a new object and the beams hit on a black screen. Move the screen around you will find see a gray (white) spot formed on the screen that is the projected laser beams. 4. ( Feature of lens ) For this vlab, we do not care about the geometrical shape and refractive index of the lens. On the top panel, you can change ‘curvature radius’, ‘refractive index’ and ‘diameter’. They are important to determine the focal length of the lens but we do not discuss their relationship. (*If you have learned the Lens maker’s equation you would be able to find out the relation of the focal length and the geometrical shape of lens.) For today’s lab, larger values of ‘curvature radius’, ‘refractive index’ and ‘diameter’ will provide you with better results (or easier configuration to measure) 5. Play with the simulator until you get used to it. Part 1 Lens equation for real image 1. ( Set-up ) Choose ‘ Principal rays’ , ‘ Screen ’ and ‘ Rulers ’ ; you will see a configuration like below. Choose large values for ‘curvature radius’, ‘refractive index’ and ‘diameter’. If the refractive index is too small, a merged point may be formed too far away from the lens to measure. Focal points Page 2

(PHY 156) This datasheet is due May.15 __________________________________________________________________ Part 2 Lens equation for virtual image 1. ( Set-up ) Choose ‘ Virtual image’ , ‘ Principal rays’ , ‘ Screen ’ and ‘ Rulers ’. Choose large values for ‘curvature radius’, ‘refractive index’ and ‘diameter’. If the refractive index is too small, a merged point may be formed too far away from the lens. 2. ( Experiment ) Place the light stand anywhere between the lens and focal point . You will see virtual (green) light beams merged at a point on the left side of the simulator. (*White light beams represents the actual beams emitted from the light stand while the green light beams are virtual beams; the green lines were artificially drawn by extending the white transmitted lines backward.) Then, using the ruler, measure the object distance d o (distance between the emitting point and center of the lens) and image distance d i (distance between the center of lens and the merged point of virtual green light beams). Make sure the image distance is negative . (Consider why.) 3. Repeat step 2 one more time but for a new location of the light stand. Focal length f [cm] Object distance d o [cm] Image distance d i [cm] 1 f [ c m − 1 ] 1 d o + 1 d i [ c m − 1 ] % difference between 1 f and 1 d o + 1 d i [ % ] Sample 61 42 -136 0.0164 0.0165 ¿ 0.0164 − 0.165 ∨ ( 0.0164 ¿ =0.6 Trial 1 75 50 -179 0.0133 0.0142 6.56 Trial 2 50 30 -100 0.02 0.023 13.95 d i d o f Page 4

(PHY 156) This datasheet is due May.15 __________________________________________________________________ (post lab question) Make a conclusion. Our experiment explained the difference between the lens equation for a real image and a lens equation for a virtual image. It shows us the precisely the focal point, the difference between the object distance and the image difference. Page 5