Collecting Light Intensity Data
Using the TI-92 and the TI-CBL

This page contains general instructions for collecting light intensity data using the TI-92 and TI-CBL. Your usual browser window may still be open. If so, you should arrange these two windows so that they overlap and you can easily switch back-and-forth between them by clicking on the exposed portion of the inactive window to make it active.

The first step is to load the TI-92 program below into your TI-92. There are three ways to do this.

• If you have the TI-92 Graph Link program and the Graph Link cable then you can download the program from your computer to the TI-92 in the usual way.

• If the program is on another TI-92 then you can transfer it to your TI-92 using the linking cable.

• As a last resort you can type the program in.

light

There have been numerous problems downloading programs for TI graphing calculators using the method above. If that method works, it is very clean. Sometimes, however, it doesn't work. In that case we can fall back on an older method, uuencoding, that is less user-friendly but more reliable. Click here for more information about this method. Then click here for a uuencoded (text file).

Connect the TI-92 to the TI-CBL using the linking cable. Plug the light probe into the CH1 port on the TI-CBL. Then run the program light from your home screen by typing light() and then pressing the ENTER key in the usual way. You should see the screen at the right. The TI-92 is giving you the opportunity to skip setting up the CBL and, if you have already collected the data using the CBL, immediately retrieve the data. To skip the set up type 2, press ENTER, and click here. To set up the CBL type 1, press ENTER and then click here. You also have the option of using the TI-CBL as a light meter, making but not recording light intensity readings. To use it in this mode type 3 and then press ENTER. You should see the screen at the right.

If you are setting up the CBL to record light intensity readings you should see the screen at the right. The TI-92 is prompting you for the time between successive measurements. Type the appropriate number and then press ENTER.
You should see the screen at the right. The TI-92 is prompting you for the number of measurements. Type the appropriate number and then press ENTER. Now you are ready to run the experiment. You may disconnect the TI-92 from the CBL if you want to use it while the experiment is going on. In this case you will need to rerun the program light, skipping the CBL setup as described above.

You should see the screen at the right or, if you skipped the CBL set up, you should see the two lines at the bottom of the screen. Press ENTER to retrieve the data from the CBL.
You should see the screen at the right. The data from the experiment is now in your TI-92.

• The list l1 contains time data. The first entry is zero and subsequent entries are the times at which subsequent light intensity readings were made measured in seconds after the first reading. Notice that the times are slightly different than expected because of the time required to make and store the readings.

• The list ch1 contains the light intensity readings in degrees Celsius made by the light probe that was connected to channel 1.

You can analyze this data using your TI-92 or you can upload it to your computer and analyze it there using your computer algebra system. The button at the right leads to a help module for uploading data to your computer from the TI-92.