# Physics307L F09:People/Ierides/Oscilloscope

## Oscilloscope

SJK 22:05, 14 September 2009 (EDT)
22:05, 14 September 2009 (EDT)
Great job with this lab summary! As I mentioned earlier, I think it's a very good example of what I'm looking for in the informal summary. Different labs will require different things, but I think you get the idea.

In this lab we used an oscilloscope following the Oscilloscope Lab Instructions and obtained significant knowledge as to its usefulness and applications. The main overview and summary of the procedure of the lab is provided by this link:

Oscilloscope Lab Instructions
The following link leads to the Oscilloscope Lab entry that includes my data, procedure, and observations:
Oscilloscope Lab Notebook Entry

### Data Summary

1. Fall Time Using "Cursor": 50.4 ± 15 ms SJK 22:00, 14 September 2009 (EDT)
22:00, 14 September 2009 (EDT)
Kudos for reporting the measurement along with uncertainty! As I mentioned in class today, we'll spend the next couple months learning how to do this more and more rigorously. One very good thing about what you did is you very clearly discussed how you arrived at your uncertainty, so the read (me) could easily determine where your uncertainty statement came from. A final note, and we'll discuss this more in class: since your uncertainty was so large, you don't need the 3rd significant digit on your best guess value. So, it'd be better to say (50 +/- 15) ms
2. Fall Time Using "Measure": 83.8 ms
During our lab we experienced errors in our values using the 'measure' function on our oscilloscope. Because the discrepancy between the two is very large, we decided to use the value that we estimated with the cursor to an error of ± 15 ms to make it more reasonable since + 15 ms meets the measure halfway but still not sure as to whether or not this is correct. We also decided to not include our 'measure' value because of its falsity throughout our lab. Since the 'measure' wasn't functioning properly, I would have replaced the oscilloscope to see if the 'measure' function was working better and I would have repeated the lab and taken more measurements, but my lab partner and I had ran out of time. The time that we had decided to use to find the time constant, $\displaystyle \tau$ , was our 'cursor' value of 50.4 ms:
$\displaystyle \tau\equiv -t\div \ln (V_f/ V_i)$
$\displaystyle t=50.4$
$\displaystyle V_f/V_i=0.1$
$\displaystyle \tau\equiv-(50.4 ms)\div \ln (0.1)$
$\displaystyle \tau\approx 21.9 ms$

### Conclusion

What I've learned in this lab was how to use an oscilloscope and how to use some of its features and functions. I've never used one before so this was an exciting opportunity to learn about its uses. In particular I've learned about triggering, the difference between AC and DC coupling, how to interpret an input signal by manipulating it on the screen as well as how to make useful measurements using some of the functions such as 'measure' and 'cursor'. These skills hopefully should improve throughout this semester as we apply them to the following labs.

We didn't get a chance to proceed beyond the AC Coupling section because we were falling behind a bit with time. It wasn't the fact that there wasn't enough time, but because of the inexperience with oscilloscopes we were just a little pressed for time with learning about its functions, etc.

Overall I found this lab to be very educational and I appreciated learning about something that can be very useful in the lab.SJK 22:03, 14 September 2009 (EDT)
22:03, 14 September 2009 (EDT)
That's great that you learned so much! No problem that you didn't get past the AC coupling.