User manual TEXAS INSTRUMENTS THE CBL 2 SYSTEM GETTING STARTED

[. . . ] Getting Started with the CBL 2TM 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. Connecting 115/230 Volts AC to any input probe may cause serious injury or electrical shock, and may damage the unit. Low-Voltage Unit WARNING! [. . . ] Repeat the procedure above, making a series of light measurements from different distances. After you have made all your measurements, press to end the data collection phase of this experiment. The screen below shows the results from a typical run. Analysis Work through the questions on the Student Data Reporting Sheet. This experiment looks at a simple relationship but there are many potential sources of experimental error. You will attempt to identify as many potential sources of error as possible and either minimize or compensate for these problems. 2000, 2003 TEXAS INSTRUMENTS INCORPORATED GETTING STARTED WITH THE CBL 2TM SYSTEM 43 Going Further One way to determine the effects of measurement errors is by using theoretical predictions. Assume that a function of the form I= A d2 correctly represents the relationship between light intensity and distance. What does this say about the relationship between a light intensity reading made at . 5 meter and one made at 1 meter?What if the reading that was supposed to be made at . 5 meter was actually made at 45 cm and the reading that was supposed to be made at 1 meter was actually made at 1. 05 meters?If you do everything you can to minimize all the sources of error, what sources are left?How might the remaining errors affect your data? 44 GETTING STARTED WITH THE CBL 2TM SYSTEM 2000, 2003 TEXAS INSTRUMENTS INCORPORATED Student Data Reporting Sheet 1. If you connected the points on the graph, describe the general shape of the graph. 2. Use | and ~ to determine the measurements from the graph, and record these measurements in the table below: Distance Light Intensity 3. Theoretically the relationship between light intensity and distance is given by a function of the form I= A d2 where I is the intensity of the light and d is the distance from the tip of the light probe to the light bulb. If this is correct, what would you expect the ratio to be between the light intensity measurements made at . 5 meter and 1 meter? What would you expect the ratio to be between the light intensity measurements made at 1 meter and 2 meters? What would you expect the ratio to be between the light intensity measurements made at 1. 5 meters and 3 meters? 4. Compare the ratios from the actual data to your predictions above. 2000, 2003 TEXAS INSTRUMENTS INCORPORATED GETTING STARTED WITH THE CBL 2TM SYSTEM 45 5. There is probably some difference between the predictions and the actual data. This frequently happens. One possible source of experimental error is in measuring the distance from the tip of the light probe to the light bulb. Make several different measurements trying to place the tip of the light probe exactly 1 meter from the light bulb. There are a number of things you can do to try to minimize this source of error. Describe some possibilities. 8. You can investigate the effects of errors in measuring the distance from the tip of the light probe to the light bulb by deliberately making errors. What is the effect of an error of 5 cm when the distance is supposed to be . 5 meter? 9. What is the effect of an error of 5 cm when the distance is supposed to be 1 meter? 10. [. . . ] Default values are shown in boldface type. Command 0 Clears and resets system {0} Clears data memory back to power-up state. Clears error information; does not clear FLASH memory. Command 1 {1, 0} Channel Setup Clears all channels Clears the selected channel {1, channel, 0} channel 1 2 3 11 21 31 Analog Channel 1 Analog Channel 2 Analog Channel 3 Sonic Channel Digital Input Channel Digital Output Channel {1, 1-3, operation, post-processing, (delta), equ} operation 0 1 2 3 4 5 6 7 10 TI Voltage sensor Current sensor Resistance sensor Period measurement Frequency measurement Radiation count mode Stainless steel temperature sensor and TI temperature sensor Stainless steel temperature sensor and TI temperature sensor Analog channel setup Turns channel off Runs auto-ID sequence for this channel Reads data from the , , 10V input Reads data from the , , 10V input but scales data in Amps when using a current sensor Reads resistance on selected analog channel when using a resistance sensor Measures period of input data, CH 1 only Measures frequency of input data, CH 1 only Measures counts from radiation monitor, CH 1 only Measures temperature, values in Centigrade Measures temperature, values in Fahrenheit 11 2000, 2003 TEXAS INSTRUMENTS INCORPORATED GETTING STARTED WITH THE CBL 2TM SYSTEM B-1 12 14 TI light sensor Voltage measurement Measures relative light intensity Measures voltage on 0-5V input of selected channel post-processing 0 1 2 None d/dt d/dt and d 2/dt 2 Results Performs no post processing (RT* and NON-RT**) Calculates and returns 1st derivative of data (NON-RT) Calculates and returns 1st and 2nd derivatives (NON-RT) *RT = REALTIME **NON-RT = NON-REALTIME (delta) equ 0 1 Off On This parameter is ignored. Results Returns data without converting Applies conversion equation to data (must also send Command 4) {1, 11, operation, post-processing, (delta), equ} Sonic channel setup operation 0 1 2 3 4 5 6 7 Scales distance in meters Scales distance in meters Scales distance in feet Scales distance in meters Scales distance in feet Scales distance in meters Scales distance in feet Results Resets channel Returns distance and @time (RT* and NON-RT**) Returns distance and @time (RT and NON-RT) Returns distance and @time (RT and NON-RT) Returns distance, velocity, and @time (RT) or distance and @time(NON-RT) Returns distance, velocity, and @time (RT) or distance and @time(NON-RT) Returns distance, velocity, and @time (RT) or distance and @time(NON-RT) Returns distance, velocity, acceleration and @time (RT) or distance and @time (NON-RT) *RT = REALTIME **NON-RT = NON-REALTIME post-processing 0 1 2 None d/dt d/dt and d 2/dt 2 Results Performs no post processing (RT and NON-RT) Calculates and returns 1st derivative of data (NON-RT) Calculates and returns 1st and 2nd derivatives (NON-RT) 2000, 2003 TEXAS INSTRUMENTS INCORPORATED B-2 GETTING STARTED WITH THE CBL 2TM SYSTEM (delta) equ 0 1 Off On This parameter is ignored. Results Returns data without converting Commands use of temperature input from user when making speed of sound calculations (must also send Command 4 for temperature compensation) When programming channel 21 (Digital In), use the syntax shown below: {1, 21, operation} operation 0 1 Off On When programming channel 31 (Digital Out), use the syntax shown below: {1, 31, operation, list of values} operation 0 1-32 Clears the channel until reprogrammed Count: number of data elements in list list of values Lists values output to digital output port Note: The list of values must have one element for each count. Command 2 Data Type This command is not used and should not be sent. [. . . ]