Name (printed) ACTIVITY MIRROR RAY DIAGRAMS PROCEDURE In the drawings on this and the following pages, the arrows represent objects in front of

Transcription

1 Name (printed) AIVIY MIRRR RAY DIAGRAM PREDURE In the drawings on this and the ollowing pages, the arrows represent objects in ront o either concave or convex mirrors. Make ray diagrams to locate the corresponding images. Draw in the complete image as an arrow. For each image arrow, indicate the: - ocation o the image, (behind mirror, between and, at, beyond ) - rientation o the image arrow, compared to the object arrow, (upright or inverted) - Relative size o image compared to the object arrow, (smaller, same, larger) - ype, (real or virtual) 1

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3 ist two similarities you see between your drawing and this photograph (taken by Alex Bond-Bishop, lass o 2010) ist two similarities you see between your drawing and this photograph (taken by Alison Haro, lass o 2006) ist two similarities you see between your drawing and this photograph (taken by Ryan Warner, lass o 2010) GE HEKED BEFRE MVING N

4 AB REFEIN FRM A URVED MIRRR INRDUIN PAR 1 Images produced by mirrors can be deined according to their style. tyle reers to our particular qualities o the image: its distance rom the mirror (compared to the object), its size (compared to the object), its orientation (compared to the object), and its type (real or a virtual image). Plane mirror images are simplistic they always have the same style. Wherever you put the object, the image is always the same distance behind the mirror as the object is in ront, always the same size as the object, always upright, and always virtual. urved mirrors (concave or convex) produce images with much more variety. he image produced by a curved mirror can be closer to, arther away, or even the same distance rom the mirror as the object. he image can be larger, smaller, or the same size. It can be the same orientation as the object or inverted. Finally, curved mirror images can be either real or virtual. o with all these options, it might seem impossible to look at curved mirror images with any sense o order and simplicity. However, it turns out that with concave mirrors there are only our dierent styles o images. he style changes when the object moves rom region to region in ront o the mirror. he most important goal o this lab is to discover these our styles and understand what the rationale or the regions that they occur in. PREDURE (PAR 1) 1. Place the light bulb on the table so that all parts o the ilament are the same distance rom the relecting portion o the mirror (these are ront-surace mirrors, so please don t touch the relecting surace). hen use a 3 x 5 card to catch the image. his can be a bit diicult at irst and takes a bit o practice. (It can also be impossible. Remember, i the image being produced is virtual, it cannot be projected onto the card and will instead be behind the mirror.) 2. Practice moving the light bulb closer to and arther rom the mirror until you get good at predicting what the image will do. When you eel like you ve got the hang o this, complete the statements below. When comparing size use smaller, larger, or same size. When comparing orientation use upright or inverted. a. When the image has a greater distance rom the mirror than the object (light bulb ilament), the image size is than the object and its orientation is. b. When the image has a smaller distance rom the mirror than the object, the image size is than the object and its orientation is. c. When the image has the same distance rom the mirror as the object, the image size is than the object and its orientation is. 3. here is a pattern between the image distance and the image size (compared to the object). What is that pattern? 4. o ar, all the images you ve produced are real images (you were able to project them onto the card). Now get the object very close to the mirror. You ll produce a virtual image that you will need to look into the mirror to see. ooking at the image, you should be able to see two undamental dierences between this virtual image and the real images you produced earlier. What are these two dierences? 4 GE HEKED BEFRE MVING N

5 REFEIN FRM A URVED MIRRR (NINUED) INRDUIN PAR 2 AND 3 I you don t like math, it s probably because you learned it in a math class. he problem with learning math in a math class is that it s typically taught and learned out o context. ake calculus, or example. Many o you are taking that class this year. You ll learn lots o rules and methods and techniques. But calculus had one purpose when it was invented. Isaac Newton developed calculus because he needed it to understand the physics o gravity. hat s it! Math is a language, much like the languages you might be learning in the World anguage Department. Nature speaks math. he will communicate with you and even give up her ways and her secrets, but only through math. o don t be a math-hater. We won t be using super-sophisticated math in this class and when we use math, it will never be or math s sake. Instead, we will use math to communicate with nature. o let s see how that works. We ll start with this: 1 = 1 d o + 1 d i. hat s the mirror equation, where is the ocal length d o is the distance an object is rom the mirror d i is the distance the image is rom the mirror What nature is saying with this mathematical equation is that there is a speciic relationship between the ocal length o a mirror, the distance an object is placed in ront o that mirror, and the position where the image will orm. I the object is moved, the equation will speciy where the new image position will be. You can use algebra to express the mirror equation as: = d od i d o +d i. In this orm, it is easy to measure an object distance and an image distance and then calculate what the ocal length must be. hat s the next goal o the lab determine the ocal length o your mirror. As you did in Part 1, you ll use the same light bulb ilament and 3 x 5 card as your object and image. A inal goal o the lab is to link what you did in Part 1 with what you do in Part 2. As mentioned beore, there are our dierent styles o images that can be produced by a concave mirror. he style changes when the object moves rom region to region in ront o the mirror. he object regions are: 1. Between the mirror and the ocus,. 2. Between the ocus and the center o curvature,. 3. At. 4. Beyond. Your job is to establish the style o image produced when the object is within each o these regions. PURPE o become amiliar with the nature o the images ormed by a concave mirror. peciically, you will discover: 1. How to determine the ocal length o a curved mirror 2. What the style o the image is (position, type, orientation, and relative size) when the object is in the ollowing positions: between the mirror and the ocus,, between the ocus and the center o curvature,, at, and beyond. d i d o Figure 1: et up or collecting real image data. Be careul to make measurements to the ilament o the light bulb, rather than the glass part o the bulb. Figure 2: Real Image projected on card 5

6 PREDURE (PAR 2) 1. ape down a piece o white ticker tape approximately 1.5 meters long. 2. Place the mirror at one end on a piece o clay. 3. Direct the relecting portion o the mirror directly down the ticker tape. Make a mark on the tape to indicate where the relective surace o the mirror is. (hese are ront-surace mirrors.) 4. Place the light bulb on the table so that all parts o the ilament are the same distance rom the mirror. hen use a 3 x 5 card to catch the image (see Figures 1 and 2). You can mark the object and image positions directly on the tape and then measure them later. Do this or at least three object positions (one where the object is closer to the mirror than the image, one where it is arther rom the mirror than the image, and one where the object and image are at the same location). 5. Make a neat data table below. Use a straightedge and label the columns careully. Record the object and image distances as well as the calculated ocal length. I the precision o your ocal length calculations is poor, keep taking data until it improves. It is reasonable to throw out obvious outliers beore you calculate the average ocal length. DAA AND AUAIN 6. alculate the average ocal length and center o curvature. Average ocal length, = enter o curvature, = 6 GE HEKED BEFRE MVING N

7 PREDURE (PAR 3) 1. urn your ticker tape over so that there are no markings on it. Mark the tape again where the surace o the mirror will be. Measure out rom the mirror position and mark where the ocal length and the center o curvature are. 2. Now use your light bulb to test the style o the image produced by a curved mirror or each o the object positions indicated (with the exception o the region between the mirror and the ocus). For the object position between the mirror and the ocus, use a pencil as the object and peer into the mirror, comparing the image o the pencil to the actual pencil. Use the table below to describe the image. he possible entries or the table are shown in parentheses below. Image location: (behind mirror, between mirror and, between and, at, beyond ) Image orientation: (upright or inverted) Image size: (larger, smaller, or same) Image type: (real or virtual) bject Position oncave Mirror Images Position ize rientation ype Mirror F F Beyond 3. tate how the image size changes when the object moves within (not between) each o the ollowing positions: a. From the mirror to the ocus. b. From the ocus to the center o curvature. c. Beyond the center o curvature. 4. he tables below are like the one that appears above. hese are or the much simpler plane and convex mirrors (which each only have one style o image). Use what you know about or observe in these kinds mirrors to ill in the tables using the same descriptors as you used in the table above. bject Position Plane Mirror Images Position ize rientation ype Anywhere bject Position onvex Mirror Images Position ize rientation ype Anywhere Use the tables you created on the previous page to answer the next questions. 7 GE HEKED BEFRE MVING N

8 For credit, you must provide a clear and complete explanation or each o the questions below. 5. he distance o an object rom a concave mirror is varied until both object and image distances are 100 cm rom the mirror. What is the ocal length o the mirror? a. 50 cm b 100 cm c. 150 cm d. 200 cm 6. A concave mirror has a center o curvature o 20 cm. For which object distance will the image be real, inverted and larger than the object? a. 5 cm b. 10 cm c. 15 cm d. 28 cm 7. he distance o an object rom a concave mirror is varied until both object and image distances are 50 cm rom the mirror. How does the size o the image compare to the size o the object when the object is moved out to 65 cm rom the mirror? a. smaller than the object b. same size as the object c. larger than the object 8. I you wanted to use the mirror in the previous question to help you to apply makeup, where would you place your ace in order to use it as it is intended to be used (that is, upright and magniied)? a. less than 25 cm b. 25 cm 50 cm c. 50 cm d. > 50 cm 9. You pull the bowl o a spoon closer and closer to your eye and notice that the image o your eye lips right side up when the spoon is 2.0 cm away. How ar would you put a candle lame away rom the spoon i you wanted to make the largest possible image o the lame out in ront o the spoon on a wall? a. less than, but very close to 2.0 cm c. less than, but very close to 4.0 cm b. greater than, but very close to 2.0 cm d. greater than, but very close to 4.0 cm 10. he table below lists object and image distances or objects in ront o six dierent mirrors. Identiy each type o mirror? bject Distance (cm) Image Distance (cm) ype o Mirror (Plane, oncave, onvex, or None) 8 Reason or choice GE HEKED BEFRE MVING N

9 MIRRR EQUAIN PRBEM VING In the space below, do the ollowing problems rom the hardcover book: Regular Physics: Page 659, problems 9, 10, 11, 12 Honors Physics: Page 659, problems 10, 12, 14, 20, 22 tart each problem with givens (like I taught you) and show all work. 9