Physics307L F09:People/Joseph/Lab5

Speed of Light

My final value for the speed of light was $$c=3.164*10^9$$m/s with an uncertainty of $$pm.0001 /times 10^9$$ m/s. My value was about 5% off of the accepted value, and my data and calculations can be found here

Our error was likely from our uncertainty in whether or not the PMT was consistently recieving the same amount of light, and this uncertainty would be propagated throughout the rest of the experiment. It would be a good idea to have the PMT fixed and have the polarizer mounted in some sort of a ring that you'd be able to manipulate from outside the tube. If you had a oscilloscope right with you, one with a very high resolution, you could cut this error down dramatically. It would not have been a bad idea to make a schematic of how everything is plugged, people seemed to have trouble making this experiment easily repeatable. This lab could use some improvement, and Bradley and I had to do some acrobatic solo flying on this one, but I learned a lot and it was interesting to see how one would measure something like the speed of light.