User:Randy Jay Lafler/Notebook/Physics 307L/2010/10/18: Difference between revisions
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==Procedure== | ==Procedure== | ||
* We turned on the power supplys, the T-A converter, and the oscilloscope. | * We turned on the power supplys, the T-A converter, and the oscilloscope. | ||
* We studied the wires connecting the devices together and the display of the oscilloscope until we understood what everything meant. We also asked for an explanation for Professor Koch and for Katie. | * We studied the wires connecting the devices together and the display of the oscilloscope until we understood what everything meant. We also asked for an explanation for Professor Koch {{SJK Comment|l=05:25, 21 December 2010 (EST)|c=There really is no explanation for Prof. Koch}} and for Katie. | ||
* We then pushed the LED at the end to the meter stick into the tube until it just touched the PMT, and then we pulled it out a little more than 150cm. | * We then pushed the LED at the end to the meter stick into the tube until it just touched the PMT, and then we pulled it out a little more than 150cm. | ||
* We pushed the meter stick in the tube in 10cm increments. We also rotated the PMT in the tube after every change in distance until the dip in the side of the spike was at the same level that it was for the first measurement. We matched the side of the spike to the horizontal cursor line on the oscilloscope that we set during our first measurement. This ensured that the intensity of the light was the same at each distance. The LED and the PMT both have polarizers on them, so rotating the PMT's polarizer relative to the polarizer on the LED changes the intensity of light allowed to pass through the polarizers and cause a voltage. | * We pushed the meter stick in the tube in 10cm increments. We also rotated the PMT in the tube after every change in distance until the dip in the side of the spike was at the same level that it was for the first measurement. We matched the side of the spike to the horizontal cursor line on the oscilloscope that we set during our first measurement. This ensured that the intensity of the light was the same at each distance. The LED and the PMT both have polarizers on them, so rotating the PMT's polarizer relative to the polarizer on the LED changes the intensity of light allowed to pass through the polarizers and cause a voltage. |
Revision as of 03:25, 21 December 2010
Project name | <html><img src="/images/9/94/Report.png" border="0" /></html> Main project page <html><img src="/images/c/c3/Resultset_previous.png" border="0" /></html>Previous entry<html> </html>Next entry<html><img src="/images/5/5c/Resultset_next.png" border="0" /></html> |
Speed of LightThe purpose through the setup as well as the Excel sheet and graphs are the same as in Emran's notebook PurposeTo measure the speed of light by using a T-A converter and an oscilloscope. Equipment
Safety
Setup
Procedure
DataAnalysisThe accepted value for the speed of light is 30cm/ns. We got a value of 31.5(1)cm/ns for the first trial, and we obtained a value of 32.1(19)cm/ns for the second trial. These values are both larger than the accepted value for the speed of light. The accepted value is a little more than one standard diviation smaller for both of our measurements. Even though our values for the speed of light are both larger than the accepted value, they seem to be consistent with each other. The range for our first data is 30.5cm/nm to 32.5 cm/nm, and the range for our second data set is 30.2cm/nm to 34cm/nm. So, the ranges for our data do overlap. ErrorThe accepted value of C:
Since both our data sets are larger than the accepted value by a similar amount, it is possible we had some systematic error in our measurements. Other possible error could be do to us not holding the intensity of the light completely constant. We had to turn the PMT within the tube to maintain the spike measured by the oscilloscope at the same level, and thereby keep the intensity the same. We had to do this by matching the side of the spike to the cursor line on the oscilloscope, and the spike was very sensitive at close distances to turning the PMT. I have more explanation for the error in my summary. Error in Summary Acknowledgments/CitationsEmran for the picture's, Excel sheet and graphs. |