User:Garrett E. McMath/Notebook/Junior Lab/2008/11/10/Summary

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SJK 17:08, 17 December 2008 (EST)
17:08, 17 December 2008 (EST)
You took excellent data for this lab. I am glad you went through the two-day learning process, as I think it was very valuable to you. I'm not familiar with the DART facility, but the parallel with the delay issue sounds interesting. Of course, you have far too many digits on your uncertainty (and value)! And you don't make a statistical comparison with the accepted value.

Lab Summary

I found this to be an eye opening expirience. The fact that we were able to measure the fastest speed allowed using fairly simple apparati is just amazing. This was however a more difficult lab than ones previous. It used quite a bit more equipment than we were used to and therefore took us nearly an entire lab period just to get to the point where we were comfortable in what we were doing and able to take data. Even after that it wasn't until our final set of data on the second day that we were able to use all the facets of the equipment and get very accurate data. All in all it was a slow learning curve but a valuable one at the end. If we were ever to do this again I would certainly hope I will read this lab and forego much unnessesary hassle by immediatly using a sufficient delay and using the stop feature on the oscilloscope to keep the variances to a minimum. The time delay I found to be one of the most interesting features of this lab as I know from real world expirementalists it is an incredibly prolific feature in labs. In our case the discrepency in the length of the cables running from the PMT as compared with the cable runniing from the emitter was not to big and could be handled with a mere 10ns delay which corresponds to about ten extra feet of wire in the delay box however I happen to know that at the DART facility at LANL they have to use miles of delay cable for the x-ray photographs they take of simulated nuclear explosions. So in the end using our last data set we were able to get a very good approximation of the speed of light.

  • Speed of light measured from slope:2.985124E8 m/s
  • Uncertainty:.114343435E8 m/s
  • Accepted value for speed of light:2.99792458E8 m/s
  • Percentage error:.4426981%