Jim, Yes, it makes a very nice demo (I did this as an experiment in college, using a hp 5245L).
Set up LED/laser diode, mirror (or other optics), and photo detector so that you create an oscillator (it will be many MHz); each pulse received generates one pulse out. Measure the frequency. Then simply move the mirror by a few dX cm. Again measure the frequency. From this you can calculate c. The beauty of this method is that only numbers you need are dF (=F1-F2) and dX. Within reason, all the rest of the factors cancel out; no measurement or calibration is required. For added fun, start with a similar pulse-echo-oscillator using sound. Almost everyone of any age knows about canyon echoes, PA system feedback, or counting seconds between lightning and thunder. So (like a trombone) move the speaker/microphone a few dX feet. Again, all you need is dF and dX to calculate the speed of sound. The speeds differ by almost exactly a factor of a million (sound travels about one foot per millisecond; light travels about one foot per nanosecond). It should make a stunning audio & visual demo. /tvb ----- Original Message ----- From: "Jim Palfreyman" <jim77...@gmail.com> To: "Discussion of precise time and frequency measurement" <time-nuts@febo.com> Sent: Sunday, June 23, 2013 4:03 PM Subject: [time-nuts] Measuring speed of light or reproducing a metre > Hi all, > > With a 3325B, a 5370B, and other time-nut miscellany, what's the quickest > way you can come up with to measure the speed of light OR reproduce the > metre. > > I've got some ideas, but I'd like others' thoughts. > > Jim _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
