“Lab” 1: Measurements and Uncertainty Objective In this “lab” activity, we will explore the basics of how best to take certain kinds of measurements and different methods of estimating uncertainty in our measurements. Background Whenever we work in a laboratory environment (or even in our day-to-day lives) and attempt to take a measurement, it is almost always the case that that measurement has some uncertainty. Uncertainty refers to the fact that we can’t know the true value of the quantity we were attempting to measure. As scientists, we have a responsibility to try and estimate how far off we think our measurement is from the true value. Of course, since we don’t actually know the true value, at best we can only estimate the uncertainty. For a much more detailed discussion of all this, I strongly encourage you to read the “error_analysis.pdf” document on Google Drive. Uncertainty results from error in our measurements. Generally speaking, there are two types of errors: 1. Systematic errors, which result from some flaw in our measurement process or some factor that we didn’t properly account for. Systematic errors can be very challenging to deal with because we might not even realize they are present. Example: have you ever seen one of those spring scales used in the produce area of the grocery store? What if I handed you a very old spring scale and asked you to measure the weight of some objects… would you maybe worry that after many years of repeated use, the spring in the scale has been stretched out and now the device no longer tells you an accurate weight? Indeed. This is an example of a systematic error. One of the tell-tale signs of a systematic error is that it skews your results in one direction only (e.g., all the objects appear to weigh more than they actually do). 2. Random errors, which result from circumstances that randomly change the way a measurement turns out each time it is performed. These errors are easier to handle because we can take repeated measurements to get a sense of how much random error is affecting the outcome (more on that later). Example: suppose you want to measure how long it takes for an object to fall from a certain height down to the ground. A group of you and your friends take turns with one person being in charge of dropping the object and another being in charge of timing the descent with a stopwatch. There are many sources of random error here: ○ Does each person drop the object from exactly the same height? No, some will release it a little higher and some will release it a little lower. ○ ○ Does each person operating the stopwatch have the same reaction time? No, some will probably start and stop the clock a little too early while others will start and stop a little too late. Are you doing this experiment outside? Is there wind, which could affect the rate at which the object falls? In this lab, we hope to develop some techniques for estimating the error in our measurements. Some more vocabulary before we move on: ● Accuracy refers to how close our measurement is to the true value (we don’t know how accurate our measurements are in most cases). ● Precision refers to how consistently we get the same value each time we perform a measurement (we can easily test the precision of our measurements simply by taking them many times). In our common language, we use these words interchangeably, but, as you can see, they have quite different meanings. A measurement can be accurate, but not precise or precise, but not accurate. Ideally, measurements would be both accurate and precise; and, worst case scenario, a measurement is both inaccurate and imprecise. Also, the following quantities pertaining to a set of data values, will be useful in today’s lab and in the future: ● Average (or mean): this is the usual arithmetic mean that you’ve surely learned about in past math classes. ● Standard deviation: this tells us how spread out the data points are from their average. ● Standard error (or standard deviation of the mean): this one is trickier. Imagine you performed an experiment in which you measured the same quantity, say, ten times. You could calculate the average, but you’d have no way of knowing how different that average would be if you had collected a different ten data points. So you repeat the entire experiment and get another ten data points and compute their average. Then you do it again and again until you’ve accumulated several averages. Now you could take the standard deviation of the averages and this would be a measure of how much uncertainty (or error) there is in the average. This quantity is called the standard error. However, we don’t actually want to have to perform the experiment many times, and we don’t have to. We can collect just one set of ten data points and find the standard error from these alone by applying one more mathematical step after finding the standard deviation. All of the formulas for calculating these three quantities are in the “error_analysis.pdf” document. You will need to consult it in order to complete this lab assignment. Warm Up Questions 1. Can you think of a type of measurement that always has zero uncertainty (i.e., perfectly accurate)? (Hint: this type of measurement doesn’t require any measuring devices, equipment, or instrumentation.) 2. Suppose I drew a triangle, handed you an old protractor, and asked you to measure the three angles inside the triangle. What kinds of errors might affect your measurements? Say whether the errors are systematic or random. 3. Suppose I asked you to measure your own height and I hand you a pencil and a tape measure. You have to take the measurement by yourself. Design a method for accurately measuring your height. Consider as many sources of uncertainty as you can think of and say whether they are from systematic or random errors. (If you happen to have a tape measure lying around, perhaps give this a try to help you see what issues you might encounter.) 4. Suppose I handed you a large stack of papers, 1000 pages to be exact, and a brand new ruler. I then instruct you to tell me the thickness of a single sheet of paper. What method would you use to do this? What critical assumption are you making when you use this method? Quantitative Analysis We will now practice estimating and calculating uncertainties for different types of measurements. There are two main methods: (1) estimating uncertainty from a single measurement and (2) estimating uncertainty from repeated measurements. 1. The measurement you have to do is to measure the length of some object using a standard metric ruler. The smallest markers on the ruler show millimeters (mm). a. If the object in question was a large LEGO block, what uncertainty might you estimate for your length measurement? I’m looking for a number here, which is typically given in the format ± ___ mm, where you fill in the blank. Explain. b. If the object in question was a piece of yarn, what uncertainty might you estimate for your measurement? Why is this different from in the previous part? c. If the object in question is a tennis ball and you’re trying to measure its diameter, what uncertainty might you estimate in this case? Explain. 2. Consider an experiment where you roll a ball down a ramp and the goal is to figure out how long it takes for the ball to reach the bottom of the ramp assuming it is released (from rest) from the same point on the ramp each time. To try and reduce systematic error, your labmates and you take turns being in charge of releasing the object and operating the stopwatch, which introduces some random error. Your group takes the following ten measurements: Trial 1 2 3 4 5 6 7 8 9 10 Time (s) 0.78 0.73 0.76 0.81 0.70 0.77 0.78 0.72 0.83 0.75 a. First, calculate the average (or mean) of the ten measurements. This is your best estimate of the actual time of descent. Be sure to include the units. How many significant figures should you have? (Consult “error_analysis.pdf”) b. With a repeated measurement of the same thing like we have here, we can use formulas to find an estimate for the random error in our average. This is the standard error, discussed above. So now is the time to go look up those formulas and apply them here. You need to first find the standard deviation (be careful; the N-1 is under the square root) and then you can find the standard error. How many significant figures should it have? Do you not use any software to skip doing the calculations by hand (though you can feel free to check your work with software); show your work in the space below. Plant Evolution and Physiology What you should know after this lab: • Greenhouse collection • Recognize a representative Bryophyte, Pterophyte, Gymnosperm, and Angiosperm • Major differences between the moss, fern, pine and flowering plant life cycles • Recognize gametophytes and sporophytes in the above life cycles • How to measure plant structures (e.g. to compare gametophyte and sporophyte sizes) • Recognize structures involved in vascular plant transpiration (stomata, tracheids, xylem) • How to make a cross-section mount of a stem to find vascular bundles, xylem, and phloem • The effects of environmental conditions on transpiration rates • How to measure plant transpiration rates • What a flower is, and the function of each part of the flower • The identifying characteristics of monocots and dicots Skills that you will reinforce from previous labs and Activities: Measurement, microscopy, and basic plant anatomy I. Greenhouse Tour This lab will introduce you to three major land plant lineages, which evolved from a Chlorophyte (green algae) ancestor. These lineages are the gametophyte dominant, non-vascular mosses, the sporophyte dominant, vascular ferns, the heterosporous, contained-gametophyte, seed-producing, vascular gymnosperms and angiosperms. If they choose, your instructor will lead you on a brief tour of the CSUS Greenhouse facility. Please observe the diversity of mosses, ferns, gymnosperms and angiosperms. See if you can identify gametophytes and sporophytes in each. II. Mosses (Phylum Bryophyta) are the most primitive land plants, which emerged onto land around 475 million years ago. They are considered non-vascular because they lack tracheids, but indeed possess leptoids and hydroids (vascular-like, water conducting tissues), and are gametophyte dominant. Sperm from the antheridia of the male gametophytes need water to swim to the eggs in the archegonia of female gametophytes. A protected embryo grows from the fertilized egg or zygote inside the archegonium. This develops into a diploid sporophyte. a.) Observe the living mosses and diagrams provided to draw the gametophyte and attached sporophyte. Label each part noted above, and measure and record their respective diameter (mm) in the table below (Table 1). b.) Why do you think mosses are typically very short (height)? (Hint: What is a limiting factor in their life cycle?) 1 III. Ferns (Phylum Pterophyta) evolved vascular tissues (xylem, including tracheids in most vascular plants, and phloem) and emerged from mossy ancestors some 450 million years ago. They diversified greatly in the Carboniferous and are responsible for producing great coal deposits, as well as extracting great amounts of CO2 from the atmosphere. With vascular tissues, the sporophytes were able to grow to greater heights. Extant tree ferns can grow to 10 m tall! Meiosis occurs in the sporangia of the sporophytes. Sporangia can be found in clumps called sori on the undersides of the leaves. The product of meiosis is haploid spores. Spores germinate into tiny non-vascular gametophytes, which produce sperm and/or eggs in antheridia and archegonia, respectively. As in mosses, fern sperm must have water to swim to the eggs in the archegonia of another gametophyte. A protected embryo grows from the fertilized egg or zygote inside the archegonium. This develops into a diploid sporophyte, becomes independent of the gametophyte, develops vascular tissues and roots, and becomes a relatively large sporophyte. a.) View the living and prepared slides of the fern gametophytes. In the space below, draw a fern gametophyte, indicating the presence of antheridia or archegonia depending on the specimen that you view. Measure the diameter (mm) of the fern gametophyte and sporophytes available in lab at their widest point and record in the table below (Table 1). b.) View the underside of a blade from the provided fern sporophyte. You should be able to see a sorus and the sporangia enclosed. Some of these sporangia may have dessicated and opened, releasing their spores. Make a drawing of these structures in the space below. c.) Are ferns sporophyte or gametophyte dominant? d.) Give two similarities between moss and fern life cycles. 2 IV. Gymnosperms (including Phylum Coniferophyta) appear in the fossil record around 305 million years ago. They diversified and proliferated in the Mesozoic as Earth’s atmosphere, with its diminished CO2 levels, became cooler and drier. Gymnosperms are heterosporous, producing abundant microspores, which become pollen and contain the abundant tiny male gametophytes protected by a sporopollenin coat and the fewer female gametophytes located in the ovules of the ovulate cones. Pollen carried by the wind, lands on the sticky ovulate cones. The pollen grains germinate and produce a pollen tube containing a sperm nucleus, which fuses with the egg nucleus to form a zygote. The diploid embryo develops within the haploid female gametophyte contained within the diploid seed coat – collectively forming the seed. The seed may eventually germinate and the embryo will grow into a very large, independent sporophyte. a.) Create a wet mount of the pine pollen provided and use prepared slides of the male and female pine gametophytes to make a drawing in the spaces below. Using the calibration data from the previous microscopy lab (Lab 5), estimate the sizes of the male and female gametophytes at their widest point and record their widths (mm) in the table below. Male gametophyte drawing Female gametophyte drawing Table 1. Diameters (mm) of gametophytes and sporophytes for the major land plant lineages. Diameter Measurement (mm) Plant Lineage Gametophyte Sporophyte Moss Fern Conifer Male = Female = 3 1.5 x 104 b.) In the space below, create a single graph using the data you generated above (Table 1) to demonstrate the relationship between the diameter of gametophyte and sporophyte stages related to the major plant lineages. Hint: You will need to calculate ratio data for the vertical axis and nominal data on the horizontal axis. Do not forget to label the axes appropriately. V. Angiosperms Members of the Phylum Anthophyta (flowering plants) also are known as angiosperms. This is by far, the most diverse lineage of plants alive today. Estimates suggest that there are 275,000 species of flowering plants in existence. These plants are characterized by producing flowers that bear the reproductive structures, having the ovules (and later seeds) enclosed within an ovary, and by the presence of vessel elements in the xylem. Although many characters can be used to define lineages within the flowering plants, many of these characters are used to describe flower structure. Today, we will focus on two major lineages of flowering plants, the monocots, and the eudicots. Angiosperm means “container seed,” which refers to the ovules (and later seeds) of these plants being enclosed inside a structure called an ovary. The ovary is essentially a chamber at the base of a larger structure called a carpel. Because ovules are protected within an ovary, pollen grains must find an alternative way to reach them. Angiosperm pollen grains are generally delivered to a flower by wind or animals. The grains are deposited on the stigma, the sticky tip of the carpel. A microgametophyte develops from the pollen grain and produces a pollen tube that grows down the style, the elongated portion of the carpel between the stigma and the ovary. The pollen tube can reach an ovule inside the ovary in as little as 12 hours! Upon reaching the ovule, the pollen tube penetrates the embryo sac (the mature megagametophyte) and releases two sperm cells. One sperm cell fertilizes the egg to make the embryo. The other sperm cell unites with, or “fertilizes,” two haploid nuclei, called polar nuclei, at the center of the embryo sac. This produces a triploid tissue (three sets of chromosomes) called endosperm. The endosperm serves as the source of nutrition for the developing embryo. This process, called double fertilization, is unique to the angiosperms. The entire sexual portion of the angiosperm life cycle takes place in the flower. A flower is a specialized branch that consists of four basic whorls, or types of structures, each with a different function. The two outer whorls of the flower do not have any direct function in reproduction. The two inner whorls are involved directly in reproduction. All of these whorls are attached to an 4 enlarged piece of stem called the receptacle. The outermost whorl is made up of leaf-like structures called sepals. Sepals are typically green and protect the flower while it is developing (or in bud). All of the sepals, collectively, are called the calyx. The next whorl includes leaf-like structures that are commonly pigmented, and may also be scented. These are called petals, and are generally involved in attracting pollinators to the flower. All of the petals, collectively, are called the corolla. The next whorl consists of stamens, which are the male reproductive structures. Stamens are made up of the anther (a sporophyll with four microsporangia fused together), inside of which pollen grains are produced. The anther sits atop a stalk called the filament. The innermost whorl of the flower consists of the female reproductive structures, or the carpels. A carpel represents a single sporophyll; however some flowers have several carpels fused together into a compound ovary. After pollination and fertilization take place, the ovary develops into a structure called the fruit. This entails a thickening and/or hardening of the ovary wall, the pericarp, and possibly the development of other structures as well, such as wings or barbs. A fruit is simply a matured ovary with seeds enclosed. While we commonly think of fruits as fleshy and sweet, such as an orange or a peach, some fruits are dry and split open to release their seeds when they are mature. The ovary can be attached above or below the attachment point of all other flower parts, termed a superior- or inferior ovary, respectively. Monocots vs. Eudicots. As you are examining the flowers (and other plant parts on display today), you will notice several other characteristics that are important in identifying plants and in distinguishing the two most prominent lineages of flowering plants (the monocots and eudicots). These characters include floral symmetry (whether the flower itself has radial or bilateral symmetry), the number of floral parts in each whorl, whether or not the floral parts from the same whorl are fused into a common structure, the number of cotyledons, or seed leaves, that you see in the embryonic sporophyte (in the seed), the venation pattern in the leaves (parallel venation vs. net-like venation), and whether the flowers are found singly on a stalk or clustered into an inflorescence, or group of flowers. a.) Comparison of monocots and eudicots. Summarize the primary differences between monocots and eudicots for the characters shown below (Table 3). Your instructor will discuss this table with the class before moving on to specimen identification. Use this information as you are examining each of the flowers on display in the lab today to determine the lineage to which they belong. Table 2. Primary differences between monocots and eudicots. Character Monocots Number of floral parts Leaf Venation Number of cotyledons 5 Eudicots b.) Seed structure. A seed contains an embryo that is packaged with enough food reserves for the plant to get to a point where it can carry on photosynthesis and fend for itself. Within the seed, the type of nutritive tissue present depends on the type of seed you are examining. In most eudicots, the endosperm is absorbed by two cotyledons, or seed leaves, of the young embryo prior to being released from the parent plant. In monocots, by contrast, the endosperm serves directly as the nutritive tissue and is absorbed by a single cotyledon as the seed germinates. With your group members, observe the corn and bean seedlings and determine which is a monocot and which is a dicot (use Table 2). Draw them in the space below and indicate on the drawing how you made your determination. c.) Flower Structure. Two flower species are in the vase at your bench. One is a monocot and one is a eudicot. Your instructor will tell you the names of the species (write down the species names on the lines provided). In this portion of the lab, we will CAREFULLY dissect the flowers, and examine their characteristics and structures, and determine which one is the monocot and which is the eudicot. We will do the same for the sunflower. 1. Species #1: Examine this flower for the characteristics and parts described on the previous page, including number of floral parts per whorl, number of carpels, inferior vs. superior ovary, leaf venation, etc. Draw a picture indicating some of the important characteristics below. Is this a monocot or a eudicot? How do you know? 2. Species #2: Examine this flower for the characteristics and parts described on the previous page, including number of floral parts per whorl, number of carpels, inferior vs. superior ovary, leaf venation, etc. Draw a picture indicating each of the floral whorls and important features of these flowers. Is this a monocot or eudicot? How do you know? 6 3. Sunflowers. Examine the sunflowers (either in your vase or on the side bench). Is the sunflower a single “flower”? Do the flowers have superior or inferior ovaries? Draw a picture of a single sunflower in the space below, labeling the sepals, petals, stamens, and ovary. VI. Vascular Tissues in Plants The evolution of vascular tissues was an important development for the land plants. It offered several selective advantages, which stemmed from their newly-found ability to grow to new heights. The xylem and phloem, which comprise a vascular bundle, are used to transport water/minerals and carbohydrates, respectively. Phloem and xylem transport occurs in many directions throughout the plant, but xylem (water) transport generally moves from roots to shoots. a.) As a group (lab-bench team), obtain a sunflower seedling and use the provided razor blade to cut as thin a section of the stem as possible to make a wet mount. Draw the cross-section in the space below. Using the provided diagram, label your drawing (vascular bundle, xylem, phloem) appropriately. b.) Why were plants with tracheids (vascular tissues) able to achieve great heights, as compared to their vascular-like (leptoids and hydroids) tissue-bearing counterparts such as the mosses? c.) What selective advantage is provided by tracheid tissue and what changes in plant stature did its advent allow? The answer to the latter part of this question is provided in Section III (Ferns) above, but you will have to consider what selective advantage this provided plants on your own. 7 d.) In your drawing of plant vascular tissue above, you included the xylem and phloem. Why might water generally only travel in one direction – i.e. ultimately, where does it go? (Hint: What is one of the two major sources of atmospheric water?) VII. Plant Physiology – Transpiration The development of plant vascular tissues provided several selective advantages for land plants as they diversified and flourished. You likely noted above that water leaves the plant in a process known as Transpiration. Numerous stomata, located on the underside of most plant leaves, are pores that open and close depending on the water availability of the plant. Stomata are similar in shape to a “cat’s eye” or a zero enclosed in parentheses such as this à “(0).” Surrounding each pore of the stomata are two guard cells, which expand and open the pores when turgid and close turgity is lost (water is scarce). When water is plentiful, guard cells open the stomal pores and allow CO2 gas to enter the plant as water vapor exits. As you know, CO2 is an important component of photosynthesis and transpiration serves as one of the two major sources of atmospheric water. a.) To observe the numerous stomata, you will take an imprint from the underside of the Tradescantia spp. plant provided in class. Your instructor will demonstrate the process for you. You do not need to pick the leaves of the plant for this procedure! Draw your findings in the space below. Be sure to label the pore and the guard cells. • Briefly, you or a group member will gently brush a dime-sized patch of clear nail polish on the underside of one leaf and allow two minutes for it to dry completely. • Place a small piece of scotch tape so that it covers approximately 1/2 to 2/3 of the nail polish. • Slowly lift the tape and place it on a clean microscope slide. The stomata will be easiest to view on the portion of the nail polish not covered with tape. b.) What would be the benefit of having stomata on the underside of leaves and not the top? VIII. Plant Physiology – Transpiration in Action! Now that you know the how and why transpiration occurs, we will view the uptake and “release” of water in the lab using Camellia sinensis clippings from bushes we sampled earlier in the semester. On the rear lab benches, eight transpiration measurement stations have been set up. Your group will be assigned to one of these, from which you will take measurements and record the data in the table below. You also will record this data on the white board so that it can be compiled for all labs for further analysis. 8 a.) Each bench contains C. sinensis clippings with either three or six leaves. With your group, discuss and agree on a possible hypothesis regarding the number of leaves on these samples and their respective rates of transpiration. Write your hypothesis and rationale in the space below. b.) Use the ruler and locate the meniscus in the plastic tubing, which represents the current water level for your assigned setup. Measure this distance from the end of the tubing to the meniscus and record it in the table below (Table 3). Indicate the time of this measurement as well. In 1.5 – 2 hr, you will repeat this procedure. Do not forget to write your calculations for mm/min on the white board as well. Your instructor will compile the data and provide you a spreadsheet for your complete analysis. Table 3. Transpiration rate data for Camellia sinensis under laboratory conditions. # Leaves_________________ Meniscus Distance 1 (mm) Start Time Meniscus Distance 2 (mm) End Time Elapsed Time (min) H2O movement (mm/min) IX. Summary Question c.) List three major morphological trends in the evolution of land plants AND propose advantages associated with each. 1. 2. 3. 9 X. Transpiration Supplement During our plant evolution laboratory exercise, an apparatus was set up to demonstrate the process of transpiration using Camellia sinensis. Data was collected from each group (lab bench) concerning the rate at which water was drawn into the vascular tissue of each C. sinensis sample. These data were entered into an Excel spreadsheet for your analysis. 1.) Write a hypothesis and rationale concerning the experiment you conducted during this laboratory session. 2.) Use the data provided in the Excel spreadsheet to perform an appropriate analysis, which may or may not support your hypothesis. a.) What is your approach? In other words, tell me what you calculated and why. b.) As part of your analysis, provide an appropriate graph to illustrate your findings. Place the graph at the end of this page. 3.) Was your hypothesis supported? What is your evidence? 4.) Give two factors you think may have resulted in the outcome you determined. 10 Name:____________________________ Lab 2 – Electric Fields and Potentials Report Objectives – Verify the behavior of potential in the vicinity of parallel plates – Verify the behavior of the electric field inside parallel plates and near a neutral conductor – Demonstrate the visual relationship between equipotential lines and electric field lines Theory 1. What is the expectation for the electric field inside a parallel plate capacitor (2 oppositely charge plates)? 2. What is the expectation for the electric field at the surface of neutral conductor in an electric field? 3. What is the expectation for the electric field inside of a neutral conductor in an electric field? 4. What is the sign of the potential near a positive charge? 5. What is the sign of the potential near a negative charge? 6. As you move farther from a single charge, does the potential get larger, smaller, or stay the same? 7. Write Equation 2.1 from the manual and define all terms. 8. What is the visual relationship between equipotential lines and electric field lines? Procedure: The procedure follows the manual in set-up for the two plates, parallel plates and a neutral ring, and bar/circle. Two Parallel Bars: Two Parallel Bars Video Link 9. Complete the following data table. Fill in the voltage near each bar and each dot on the video. Dot 1 is the closest dot to the negative bar. Location Potential Difference 10. Using the video, what is the amount the potential changes when (V) the probe is tilted about 45°? + Bar 5 11. What is the amount the potential changes when the probe is moved ~1mm? 4 3 2 1 – Bar 12. The data collected is shown below. The same picture is uploaded on canvas. Using a drawing program of your choice, draw GREEN equipotential lines. The drawings do not have to be perfect but do try to go through all the dots. I highly recommend using Power Point. You can insert the image into a blank slide and use the drawing tools to make your lines. When you are done, you can take a screenshot and save it as a picture. Analysis A: 13. Discuss your equipotential lines. Are they as expected? Are there any surprises or inconsistencies? If so, what is their cause? 14. Now add electric field lines in BLUE. Remember, field lines need to be perpendicular to equipotential lines. Draw at least 5 lines between the plates and 3 lines outside the plates in the fringe area. Add arrows for direction of the field. Discuss your electric field lines. Are they as expected? Are there any surprises or inconsistencies, what is their cause? 15. Select 5 locations: 3 locations between the plates and 2 locations outside the plates in the fringe area. Choose two neighboring equipotential lines connected by an electric field line. Measure the distance along the electric field line. Draw a circle around these locations in RED. Calculate the electric filed at each of these locations. Show your calculations here: 16. How do the numerical results of the electric field match with what is expected in between the plates and outside? 17. Save your picture, print it, and attach it to the end of the worksheet. If you are using a PDF editor, you may replace the picture above with your drawing. Two Bars and A Ring Two bars and a ring video link Data B: 18. Watch the following video: 1 bar 1 diode + ring Does the potential inside of the ring change or does it stay constant? If the voltage is constant, what does that tell us about the electric field inside of the ring? 19. For our “Two Bars and A Ring”, the voltage inside of the ring should equal the voltage of the ring itself. Based on the data, what should be the voltage inside our ring? You may give a range of possible values. 20. The data collected is shown above. The same picture is uploaded on canvas. Using a drawing program of your choice, draw GREEN equipotential lines. The drawings do not have to be perfect but do try to go through all the dots. I highly recommend using Power Point. You can insert the image into a blank slide and use the drawing tools to make your lines. When you are done, you can take a screenshot and save it as a picture. Analysis B: 21. Discuss your equipotential lines. What is happening close to the neutral conductor? Why? 22. Now add electric field lines in BLUE. Remember, field lines need to be perpendicular to equipotential lines. Draw at least 8 lines between the plates. Some of these lines should hit the ring. Add arrows for direction of the field. Discuss your electric field lines. Are they as expected? Are there any surprises or inconsistencies, what is their cause? What is happening to the charges within the neutral conductor? Use RED to show where there is any excess positive or negative charge. How will this affect the electric field? 23. It is said that you are safe in your car during a lightning storm. Based on your observations, why should this be the case? What if your car was made of plastic, would you still be safe? 24. Save your picture, print it, and attach it to the end of the worksheet. If you are using a PDF editor, you may replace the picture above with your drawing. The Bar/Circle The Bar/circle video link. Data C: 25. The data collected is shown above. The same picture is uploaded on canvas. Using a drawing program of your choice, draw GREEN equipotential lines. The drawings do not have to be perfect but do try to go through all the dots. I highly recommend using Power Point. You can insert the image into a blank slide and use the drawing tools to make your lines. When you are done, you can take a screenshot and save it as a picture. Analysis C: 26. Discuss your equipotential lines. 27. Now add electric field lines in BLUE. Remember, field lines need to be perpendicular to equipotential lines. Draw at least 8 lines from the circle to the bar. Add arrows for direction of the field. Discuss your electric field lines. Are they as expected? Are there any surprises or inconsistencies, what is their cause? 28. Save your picture, print it, and attach it to the end of the worksheet. If you are using a PDF editor, you may replace the picture above with your drawing.