EMAT 3500: Light Intensity with CBL

EMAT 3500: Light Intensity with Light Sensor, EasyLink and TI-Nspire

In this experiment you will investigate the relation between Light Intensity and Distance from the light source using a light sensor, EasyLink and the TI-Nspire. Instructions for Collecting the Data using a Free-standing Light Bulb 1. Arrange the free-standing light bulb so that the bulb is level with your table-top. Tape 2 meter sticks end-to-end along the table top with the zero end at the light-bulb. 2. Place the light sensor taped to another meter stick along side the stationary meter sticks with the end of the light-sensor at the 50 cm mark on the first meter stick. This fixes the starting position of the light sensor 50 cm from the flashlight. Turn on the free-standing light bulb and turn off the overhead room lights. Close all doors and cover any windows. 3. Connect the EasyLink to the Light Sensor. Turn on your TI-Nspire and open a New Document with a NOTES page. 4. Plug the EasyLink into the TI-Nspire. a. Choose a Lists & Spreadsheets application for the Light Sensor. b. A spreadsheet opens with the Data Collector at the bottom. c. Press Menu->1: Experiment->3: Setup Collection->2: Events with entry 5. Press enter twice for the first data entry. A pop-up window should appear. Enter the measurement showing on the fixed meter stick (in cm) (this should be 50 cm if you have set things up as described above), then press Enter to record the data into the spreadsheet. 6. Move the meter stick with the light-sensor 5 cm further from the light bulb (make sure it is still lined up with the fixed meter sticks). 7. Press Enter once (a pop-up window should appear) and enter the next measurement for the distance of the light-sensor from the bulb. Press enter to record the data. 8. Repeat steps 6 and 7 until the light sensor is at the end of the first fixed meter stick (100 cm). Your last entry should then be 100. 9. Tab over to the x-box on the Data Collector to close it and disconnect from the EasyLink. 10. The data in column A should start with 50 and end with 100. These data should be the actual distances of the sensor from the light source. 11. Insert a new Graphs & Geometry page and change the Graph Type (Menu->3) to Scatterplot (4). 12. Change the Window Settings (Menu->4: Window->1: Window Settings) to the following: XMIN: 45, XMAX: 105, YMIN: -0.2, YMAX: 0.6 13. Choose dc01.event for the x-variable and dc01.light1 for y-variable. 14. Change Graph Type to Function (Menu->3: Graph Type->1: Function). 15. Based on your data, the shape of the scatterplot and the situation, choose a function type and enter a reasonable approximation of that function type to fit this data. Create a slider or two for your parameters. You can adjust your parameter sliders to get a better-fit function. (Hint: Light is supposed to vary as the inverse square of the distance.)