# Physics307L:People/Carrillo/Speed of Light

## Speed of Light Lab Summary

SJK 12:33, 22 October 2010 (EDT)
12:33, 22 October 2010 (EDT)
The scope of this summary is good. The main things missing, which are very important, are the uncertainty and statistical comparison with the accepted value, as noted below.

### Brief Overview

The purpose of this lab was to measure the speed of light, $\displaystyle c\,\!$ . To measure this, we used pulses from an LED light with a high speed detector and a delay module in a direct time of flight measurement over varied distances. The PMT, TAC module, and the o-scope helped us succeed in making mearurements for this lab. We graphed the voltage readings from the o-scope versus the distances between the PMT and LED light, and therefore we were able to calculate the speed of light by finding the best fit linear slope.

### Our Data Results

SJK 12:32, 22 October 2010 (EDT)
12:32, 22 October 2010 (EDT)
Our average measured value of the speed of light is...
• $\displaystyle c_{measured, average}=11.69289469\frac{cm}{ns}\,\!$
The accepted value of the speed of light from Wikipedia is...
• $\displaystyle c_{accepted}=29.98\frac{cm}{ns}\,\!$

## Error

$\displaystyle \% error=\frac{c_{accepted}-c_{measured, average}}{c_{accepted}}\,\!$

therefore our percent error is...

$\displaystyle \simeq61%\,\!$
• Please see the section about our error in my lab notebook.

## Conclusion

In conclusion, I learned a lot from this lab and I thought that the lab was really interesting. The hardest part of this lab to me was getting started with the setup and figuring out what types of settings we needed to have for the equipment. We did not get a close value to that of the accepted value of the speed of light, so therefore we got a pretty bad percent error. If you would like to see the reasons for this error please click on the link above in the error section. Perhaps we did not really understand the concept of timewalk, which may have given us bad data.SJK 12:33, 22 October 2010 (EDT)
12:33, 22 October 2010 (EDT)
I think you learned a lot about the equipment, and with more time, probably would have obtained better data. Please see Ginny's pages for some more comments.