Physics307L F09:People/Andrego/Oscilloscope

Brief Overview
This lab focused on the uses and functions of the oscilloscope through procedures like measuring the fall-time of a sine wave through three different methods. Topics such as AC-DC Coupling were discussed, and I learned that the different modes of coupling depended on the the scale at which one wishes to observe shifts or ripples, in the smaller scale preference we discovered that the AC setting allows us to focus the screen more easily to the signal and hence see the ripples in the wave more easily. Other topics covered included the use of the trigger function, the "rising edge" of the wave, and the RC constant where we were able to compare the results on our oscilloscope screen with the examples described in the circuits web page that we consulted. We found that the RC constant we were looking at was RC<<T. When looking at the expected value of the fall-time "tau" (evaluated by using the equation -t/[ln(Vf/Vi)]=Tau) we discovered that our data varied largely from the expected value.

Data Results
Fall-time Expected Value
 * With the Cursors = 50.4 ± 15 ms
 * With the Measure Function = 83.8ms


 * Tau=22.58 ms

Error
My lab partner Anastasia and I had great difficulty getting consistent results from our oscilloscope readings. When we would use the measure function we noticed that our values were SIGNIFICANTLY larger than when we used the cursors. For this reason we noted in our oscilloscope lab notes that we did not trust these values at all. I believe that a lot of our relative error came from the fact that neither my lab partner nor I had ever used an oscilloscope before and hence we took a lot of time trying to figure out how to use the functions and read the screen. We were unable to complete enough trials to really get consistent data.