Physics307L F09:People/Mahony/Lightspeed

Speed of Light Lab Summary
In this lab, my partner Ryan and I measured the speed of light. We did so by measuring the delay between a triggered pulse from an LED and the corresponding received pulse generated by a photomultiplier tube (PMT). The procedure we followed is outlined in | Professor Gold's manual.

Results
Our measured speed of light was: The accepted value is: For our raw data and to see how we arrived at this value, see the lab notebook.
 * $$2.9461 \pm 0.0437\times 10^{8} m/s$$
 * $$2.9979\times 10^{8} m/s$$



Conclusions
I was very pleased with this lab. Despite having to compensate for the effect called time-walk, which is a problem encountered when trying to trigger off of signals of differing amplitudes, we managed a reasonable measurement for the speed of light. In fact, our measured value was accurate to the two most significant digits.

In this lab I became familiar with lab equipment such as Time-Amplitude Converters (TACs) and photomultiplier tubes (PMTs). I started to learn how to analyze data at a basic level. I also learned the importance of scrutinizing your data and the procedure you took to determine if there are any major sources or error or if your data is relevant. I still have a bit to learn about data analysis, including more advanced techniques and the significance of the standard error of the mean.

The lab setup was intuitive once we understand what was going on, which actually ended up taking quite some time. Ryan and I thought of several several minor improvements, though I would like to highlight one. We though it would be a good idea to detach the polarizer from the PMT so it can be rotated separately. This change could possibly reduce error.

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