2007-01-15 14:05:52 · 4 answers · asked by Oriel B 1 in Science & Mathematics ➔ Physics
One of the very good experiment that I remember reading about is that of Michelson, using a rotating multifaceted mirror, basically it was a long based stroboscope. Only if the mirror was properly aligned when a beam of light struck it, it would be detected. Changing the frequency of the mirror until the beam of light would actually meet a face to bounce off in the right direction would mean that it would have traveled the distance in the time for the mirror to change from one face to another.
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2007-01-15 14:19:54 · answer #1 · answered by Vincent G 7 · 0⤊ 0⤋
It is done by shinning a beam on to a rotating mirror. At one point in the mirror's rotation, the reflected beam falls on a distant mirror, which reflects it right back to the rotating mirror, which meanwhile has turned through a small angle. After this second reflection from the rotating mirror, the position of the beam is carefully measured. This makes it possible to figure out how far the mirror had turned during the time it took the light to make the round trip to the distant mirror, and since the rate of rotation of the mirror was known, the speed of light can be figured out. These techniques gave the speed of light with an accuracy of about 1,000 miles per second.
2007-01-15 14:26:14 · answer #2 · answered by ash v 3 · 0⤊ 0⤋
Want easy proof (not the kind used to "make" the constant)?
Calculate the speed by dividing the distance from Earth to the sun (one Au), and the time the light takes to get here.
One astronomical unit is the distance from Earth to the Sun.
1AU = 149 598 000 kilometers
Time for light to get to Earth from the Sun = 8 minutes
149 598 000 kilometers divided by 8 minutes
equals= 18 699 750 Km/min.
(18 699 750Km/min)/(60sec/min)= 311 662km/s
These values are very near the answer, but are inexact because the time used was approximate.
2007-01-15 14:16:00 · answer #3 · answered by snakker2k 2 · 0⤊ 0⤋
The first accurate measurement was about 300 years before the spinning mirror experiment when Romer noticed the timing of the moons of Jupiter was off and decided it was because of the differing distances between the Earth and Jupiter. Knowing the diameter of Jupiter's orbit and Earth's could calculate the speed of light.
2007-01-15 14:37:23 · answer #4 · answered by Mike1942f 7 · 0⤊ 0⤋