Batteries. Evaluation copy

Transcription

1 Batteries Experiment 11 A battery is an electric storage device. Batteries come in many shapes, sizes, and voltages. No matter what their shape, however, all batteries have two terminals positive and negative. Some batteries have both terminals on one end. AAA, AA, C, and D batteries, however, are built with the terminals at opposite ends. The positive terminal is on the end with the bump; the negative terminal is on the flat end. Inside the battery, a chemical reaction produces electrons that collect on the negative terminal. Placing a wire between the two terminals causes a stream of electrons, called current, to flow. Voltage is a measure of the energy difference between two points in a circuit. Current and voltage can be difficult concepts to understand so some people compare them to water pipes. Current relates to the amount of water flowing in a pipe, while voltage relates to the water pressure. New household batteries have voltage values ranging from 1.5 to 9 volts; but after repeated use, the voltage decreases to the point where they are no longer able to supply enough current. In many battery-operated devices, such as calculators and digital cameras, you do not use just one battery. You group them together to form higher voltages. In Part I of this activity, you will learn to identify the different parts of a battery and you will investigate the different ways a Voltage Probe can be positioned. In Part II, you will use a Voltage Probe to measure the voltages of several different sizes of batteries. In Part III, you will measure the voltages of batteries as they are stacked together. OBJECTIVES In this experiment, you will Use a Differential Voltage Probe and NXT to measure battery voltage. Make observations about the size of different batteries. Measure the voltages of batteries as they are stacked together. MATERIALS computer LEGO NXT Intelligent Brick MINDSTORMS Edu NXT 2 software Vernier NXT Sensor Adapter NXT cable Vernier Differential Voltage Probe ruler with center groove AAA battery AA battery C battery 3 D batteries Evaluation copy PROCEDURE Part 1: Learn to use the Voltage Probe 1. Prepare the NXT for data collection. a. Connect the Differential Voltage Probe to the Vernier NXT Sensor Adapter. b. Connect the Adapter to Port 1 on the NXT using a LEGO NXT cable. c. Make sure the NXT is connected to the computer (USB or Bluetooth) and turned on. STEM 2 with Vernier and LEGO MINDSTORMS NXT 11-1

2 Experiment Launch NXT 2 Data Logging. 3. Click the Go button next to Start New Experiment. 4. Set up the experiment. a. In the Experiment Configuration window, select Vernier Voltage DVP by clicking on the pull-down list to the left of Port 1. (Notice the indicator box changes from gray to green.) b. Adjust the Duration to 15 seconds. c. Adjust the Rate to 10 samples per second. d. Click the OK button. 5. Look at the materials you will be using in this activity. a. Pick up the battery. Do you know which end is the positive end and which is the negative? Make sure everyone in your group agrees upon which is which and put the battery in the groove in the ruler. b. Now look at the red and black clips of the Voltage Probe. You will be touching the metal tips of these clips to the ends of the batteries later on. 6. Collect data using the Voltage Probe by following the steps below. You will be holding the metal clips in three different positions for approximately five seconds each. a. Click the Download and Run button to begin data collection. When the NXT beeps, touch the two metal clips of the Voltage Probe together. Hold for five seconds. b. Now, touch the black clip to the positive end of the battery (the end with the bump) and the red clip to the negative end (flat end). Hold for five seconds. c. Finally, switch the clips around so the red clip touches the positive end of the battery and the black clip touches the negative end. Hold for the remainder of the time. 7. Record your observations in Table 1. Part II: Measure the Voltage of Different Size Batteries 8. Watch as your teacher holds up different batteries. The voltage of the AAA battery is 1.5 volts. 9. Predict the voltages of the other batteries and record your predictions in the Predicted voltage column in Table Modify the experiment length. a. In the Dataset table, click on the Voltage p1-1 dataset to highlight it. b. Click the Delete Dataset button. c. Click the Experiment Configuration button in the upper left corner. d. Adjust the Duration to 3 seconds. e. Click OK 11. Measure the voltage of each battery: a. Click the Download and Run button to begin data collection. When the NXT beeps, place the red clip of the Voltage Probe on the positive (+) end of the battery and the black clip on the negative (-) end of the battery. Hold for three seconds STEM 2 with Vernier and LEGO MINDSTORMS NXT

3 Batteries b. When data collection ends, click the Analysis Tools button and select Section Analysis. c. Drag the left and right edges of the gray strip until it covers the non-zero portion of the graph. d. Record the mean (average) in Table 2 in the Measured voltage column. e. In the Dataset table, click the Show/Hide button. Note: This will turn off the graphical display so that you can collect multiple datasets, but it will not delete your data. You can always redisplay the data by clicking the Show/Hide button again. 12. Repeat Step 11 for each battery. Record your values in Table Now, read the voltage listed on the side of each battery (you may need a magnifying glass from some batteries). Record the voltage values in Table 2 under Voltage printed on battery. Part III: Measure the Voltage of Stacked D Batteries 14. Predict what you think will happen to the voltage as you add more D batteries together and measure the voltages from the end of the first battery to the opposite end of the last battery? Hypothesis: The voltage will by volts every time an additional D battery is added to the stack. 15. Place one D battery into the center groove of the ruler and measure the voltage using the method in Step 11. Record this value in Table Collect data for two stacked batteries. a. Place a second battery on the ruler with the negative end of this battery touching the positive end of the first battery. b. Hold the red clip against the positive end of the first battery and the black clip against the negative end of the second battery. c. Measure the voltage using the method on Step 11. d. In Table 3, record the voltage for two batteries. STEM 2 with Vernier and LEGO MINDSTORMS NXT 11-3

4 Experiment Collect data for the third battery by doing the following: a. Place another battery on the ruler with the negative end of this battery touching the positive end of the battery before it. b. Hold the red clip against the positive end of the first battery in the row and the black clip against the negative end of the last battery in the row. c. Measure the voltage using the method in Step 11. d. In Table 3, write the voltage for three batteries. DATA Table 1 1. When I touched the two clips together, the voltage 2. When I touched the black clip to the positive end of the battery and the red clip to the negative end of the battery, the voltage 3. When I touched the red clip to the positive end of the battery and the black clip to the negative end of the battery, the voltage Table 2 Battery type Predicted voltage (V) Measured voltage (V) Voltage printed on battery (V) AAA 1.5 AA C D 11-4 STEM 2 with Vernier and LEGO MINDSTORMS NXT

5 Batteries Table 3 Number of D batteries Voltage (V) PROCESSING THE DATA 1 battery 2 batteries 3 batteries 1. How can you tell the positive terminal from the negative terminal on a D battery? 2. Does it matter whether the red or black voltage clip is touched to the positive terminal of the battery? Explain. 3. Does size matter in the voltage values of new AAA, AA, C, or D batteries? Explain. 4. What happens when you stack multiple batteries together? 5. What do you think the voltage would be if you added together 10 batteries? Why? EXTENSIONS 1. When you measured the voltage of two stacked D batteries, you placed them on the ruler so that the positive terminal of one battery was touching the negative terminal of the second battery. Measure the voltage of two stacked batteries when the positive terminals are touching. 2. Have students predict the voltage of a dead battery. Then measure the voltage using the probes. 3. Investigate electronic devices that people might typically use during the day. Survey the kinds, sizes, and number of batteries the different devices use. 4. Compare different brands of batteries of the same type (for example, two or three brands of D batteries) to see if one particular brand lasts longer. Keep track of the cost of each battery to see if more expensive batteries are actually better. 5. Compare rechargeable and non-rechargeable batteries. STEM 2 with Vernier and LEGO MINDSTORMS NXT 11-5

6 Vernier Lab Safety Instructions Disclaimer THIS IS AN EVALUATION COPY OF THE VERNIER STUDENT LAB. This copy does not include: Safety information Essential instructor background information Directions for preparing solutions Important tips for successfully doing these labs The complete STEM 2 with Vernier and LEGO MINDSTORMS NXT lab manual includes 12 lab activities and eight projects as well as essential teacher information. The full lab book is available for purchase at: Vernier Software & Technology S.W. Millikan Way Beaverton, OR Toll Free (888) (503) FAX (503) info@vernier.com