Physics307L:People/Giannini/Oscilloscope
Oscilloscope Lab Summary
SJK 20:57, 28 September 2010 (EDT)
This is a good lab summary. It is the right scope. Also, your discussion of error/uncertainty is good. For future labs, you will know more about how to treat the uncertainty statistically, and this will be discussed in lecture.
Partner: Richard T. Meyers
Purpose
- to become familiar with the operation of the oscilloscope
- be able to measure the time constant of an oscilloscope
- know the difference between AC and DC coupling
- to understand triggering
- to become adept at using wiki lab notebook
- practice for real labs in the future
Summary We connected a wave generator to an oscilloscope and used it to produce sine, square and triangle waves. We fiddled with the settings for a sine wave, mainly be increasing the amplitude and by adding a DC Offset, and then measured the new amplitude using the grid, the cursors and the measure functions. Finally, we found a time difference between AC and DC coupling, as well as the fall time of our oscilloscope. For more on our procedure, see this link ( our procedure is found in "Setting Up" under a blue 'here' link).
Fall Time
Fall Time = 22.66 ms
We found this by using the equation V = V0* exp(-t/[math]\displaystyle{ t }[/math]) where V0 is our initial voltage and [math]\displaystyle{ t }[/math] is our fall time. We said:
V1 = V0*exp(-t1/[math]\displaystyle{ t }[/math])
and
V2 = V0*exp(-t2/[math]\displaystyle{ t }[/math])
Where t1 and t2 are the time where we measured V1 and V2 respectively.
We then divided V1 by V2 and solved for [math]\displaystyle{ t }[/math]. We ended up with:
[math]\displaystyle{ t }[/math] = ln(V1/V2)*(-t1+t2)
Our measured times and voltages can be seen here in the experimental data section.
Error
Our error is +/- 0.01 ms for t1 and t2 and +/- 0.001 V for V1 and V2. This error is due to the limits of the equipment we used (mainly the oscilloscope), since the oscilloscope would only measure to the hundreth decimal place for voltage as well as for time.
Measuring the Fall Time'
We measured the fall time by using the above method (see Fall Time). We obtained our voltage values by using the vertical cursors on our oscilloscope to estimate the highest voltage we could get and then the voltage at 30% of this voltage ( we did this to get a more accurate value of our fall time). We got our time values by using the horizontal cursors on our oscilloscope to determine the time at the voltages we had already found.
1) What Did I Learn?
- How to use an oscilloscope and wave generator
- How to make a voltage divider
- How to determine the fall time of an oscilloscope
However, I am still unsure if there are extra ways I could have measured error by evaluating certain operations done by my oscilloscope.
2) What Did I Explore Outside of the Standard Lab Procedure
I looked into a Voltage Divider, originally because I thought it was required to build one. It was annoying to find that I didn't need to use it, but it was also fun trying to make it work, although it ended with a bit frustration until I seeked out some assistance from Prof. Koch and our Lab TA Katie. They were able to make our voltage divider work in the first go through of our lab (we ended up not using the Voltage Divider in the second go through).
3) What Could Make the Lab Better Next Year?
SJK 20:31, 28 September 2010 (EDT)
Error Analysis will be a focus of this course! I like your discussion of error above, and you will get much better at it the next several weeks.
Going over error would've been nice, as it is I've only used the error that was obvious from my oscilloscope.
Citings
- Zane C. Gibson for formatting help with my Lab Data
- Antonio C. Rivera, although it seems to have been altered quite a bit by someone else due to lack of data, for the format that this summary had minus the acknowledgements.
- Professor Steve Koch - Procedure for Oscilloscope Lab
Acknowledgements
- To my lab TA Katie for asistance with finding the fall time without a voltage divider.
- To Prof Koch for help making my voltage divider work in the first go through of the lab.
