User manual TEXAS INSTRUMENTS CBL 2 SYSTEM GETTING STARTED

[. . . ] System LabPro is a trademark of Vernier Software & Technology. Radio Shack is a trademark of Technology Properties, Inc. Safety Instructions Observe all warnings, cautions, and other safety instructions indicated on the product and in the documentation. These instructions are intended to reduce the risk of injury, possible electrical shock, or damage to the unit. Never attempt to measure AC voltages from a wall outlet. [. . . ] What is the effect of an error of 5 cm when the distance is supposed to be 1 meter? 10. Another source of error is other light in the room. You can investigate the effects of this source of error by deliberately introducing an extra light and comparing measurements made with this extra light on and with this extra light off. How can you correct for extra light in the room? Repeat the original experiment doing everything you can to minimize measurement error. 46 GETTING STARTED WITH THE CBL 2?SYSTEM 2000, 2003 TEXAS INSTRUMENTS INCORPORATED Teacher Section Theory The relationship between light intensity and distance can be described by a function of the form I= A d2 but there are so many potential sources of error that students are likely to see discrepancies between theoretical predictions and the data. It is also very important for students to realize that not all such discrepancies can be dismissed as ?experimental error. ?This activity addresses this objective by attempting to identify and compensate for experimental error. The main sources of error your students should identify are: ?that is, with no light the light probe may not read zero. One way to convey the idea that not all discrepancies can be dismissed as ?experimental error?is by having students make light intensity readings using a fluorescent bulb. Because fluorescent bulbs flicker, these measurements jump around. Answers Sample data with sample answers: 1. (Intensity falls off rapidly as distance increases. ) 2. Distance . 5 1 1. 5 2 2. 5 3 3. 5 Light Intensity . 228 . 070 . 034 . 026 . 020 . 014 . 013 2000, 2003 TEXAS INSTRUMENTS INCORPORATED GETTING STARTED WITH THE CBL 2?The measurement made at . 5 meter should be 4 times the measurement made at 1 meter. The measurement made at 1 meter should be 4 times the measurement made at 2 meters. The measurement made at 1. 5 meters should be 4 times the measurement made at 3 meters. 4. For example, the actual measurement made at 2 meters is only 3. 06 times the actual measurement made at 4 meters. 5. extraneous light in the room, errors in measuring distance, the light probe is not zeroed, the light probe may not be aimed directly at the light bulb 6. Cut pieces of string to very precise lengths and hold the light probe in place by holding one end of a piece of string against the tip of the light probe and the other end in a fixed position near the light bulb. Be careful not to burn yourself on the light bulb. 8. For example, a particular reading might go up by 0. 15 11. Make two readings at each distance from the light bulb?one with the light bulb on and the other with the light bulb off. [. . . ] SYSTEM 2000, 2003 TEXAS INSTRUMENTS INCORPORATED system state 1 2 3 4 5 99 Idle Armed Busy Done Self-test Initializing code data start First point of data available for transmission to host unless host has sent Command 5 to override Last point of data available for transmission to host unless host has sent Command 5 to override System ID that was set using Command 6 data end systemID Command 8 Request Channel Status {8, channel, request type} Returns a list with three elements: E 1, E 2, E 3 channel=1, 2, 3, or 11 E 1 = sensor type (one of the operation options shown under Command 1) E 2 = last valid data read from sensor, if any [only valid when sampling is active] (not applicable to CH1 ops 5, 6, 7 or CH21 or CH31) E 3 = last valid data position (data buffer location number where that data is deposited) [only valid when sampling is active] request type=0 or 1 0 = returns current data (such as, read and return channel ID information) 1 = returns data stored when channel was last set up Command 9 Request Channel Data {9, channel, mode} Immediately reads and returns one data point. Used to verify that setup is correct. channel=1, 2, 3, or 11 Mode 0 1 Re-test input auto-ID value Return stored auto-ID value 2000, 2003 TEXAS INSTRUMENTS INCORPORATED GETTING STARTED WITH THE CBL 2?SYSTEM B-9 Command 10 alg 1 Advanced Data Reduction {10, channel, alg, P1, P2, P3. . Pn} Re-reduces data in selected channel Results Selects the HeartBeat Algorithm. [. . . ]