how did they know that the speed of electromagnetic wave is 300 000 000 meters per second?
2007-12-02 22:44:09 · 7 answers · asked by Anonymous in Science & Mathematics ➔ Physics
There is an experiment (that I did a few months ago) where it can be calculated by reflecting some laser light around the lab using several mirrors. The laser is connected to one channel of an oscilloscope and a detector is connected to the other channel. The speed of light can be calculated if you know the distance light travels from source to detector and by reading the phase difference on the oscilloscope. You also need to know the frequency of the laser light.
2007-12-02 22:52:21 · answer #1 · answered by KeplJoey 7 · 3⤊ 1⤋
Strictly, and with great pedantry, we no longer measure the speed of light.
1 metre is the distance travelled by light in 1/299792458 second. Therefore the speed of light is DEFINED as 299792458 m/s.
Use Wikipedia, not Yahoo!answers !
2007-12-02 22:59:01 · answer #2 · answered by za 7 · 3⤊ 1⤋
Ask a Scientist;
How did scientists determine the exact speed of light;;
click here to learn all about it,,
http://www.newton.dep.anl.gov/askasci/phy99/phy99388.htm
2007-12-02 22:49:59 · answer #3 · answered by SPACEGUY 7 · 2⤊ 3⤋
i hear the speed of light is 186,000 miles per second
they found this out by sending a laser beam to the moon and reflecting it back. i think it took about 2 seconds or so for the light to get back
2007-12-02 22:48:49 · answer #4 · answered by Hazza D 2 · 2⤊ 4⤋
They calculate the speed in light years, or some trillion miles per hour. They can also calculate it in standard units (mph/, m/s). Find out more on google.
2007-12-02 22:48:32 · answer #5 · answered by Anonymous · 1⤊ 5⤋
they guessed... and created tools later to prove their hypothesis by making their hypothesis the standard by which to calibrate their machine. I imagine that in 1000 years, scientists will look back and mock us for light speed as we mock those for the flat planet. Science is as rock solid as people want to believe. I personally feel that the only constant we have is math, and I think we were lucky to figure it out.
2007-12-02 22:49:20 · answer #6 · answered by blase' blahhh 5 · 0⤊ 6⤋
they run experiements and use equations
2007-12-02 22:46:16 · answer #7 · answered by chris-tea 2 · 1⤊ 4⤋