Speed of Light - Astronomybelz/phys3719/presentations/richards.pdf · • A good model for testing...
Transcript of Speed of Light - Astronomybelz/phys3719/presentations/richards.pdf · • A good model for testing...
Speed of LightSpeed of Light
Jonathan Richards
HistoryHistory• Galileo: 1667• Roemer: 1675• Bradley: 1728• Fizeau: 1849• Foucault: 1862
Galileo 1667Galileo 1667• Used laterns to measure speed of light• Not very accurate• Speed of light > 10x speed of sound
Roemer and JupiterRoemer and Jupiter• Studied the moons• Moon not on schedule• 2x10^8 m/s
Current ValueCurrent Value
c = 2.9979 x 10^8 m/s
Foucault's MethodFoucault's Method
Lab MethodLab Method
Fixed MirrorFixed Mirror
Uncertainty:3.35 x 10^6 m/s
Moving MirrorMoving Mirror
c = 2.9068x10^8 m/s
Error: 3.406 x 10^6 m/s
Linear CorrelationLinear Correlation
r = .9477, .9164, -.5617, -.8984
Chi SquaredChi Squared
6.04, 3.08, 6.64, 8.71
Residual GraphResidual Graph
ConclusionConclusion• A good model for testing speed of light• The longer the distance D, the more accurate• Accepted value for speed of light: 2.9979x10^8
m/s• Would like to try a longer distance D to see if it’s
more accurate• Would like to get the image in microscope focused
better.
ReferencesReferences• Error Analysis, Taylor, John R., 2nd edition• http://www.speed-
light.info/measure/speed_of_light_history.htm