Re: [time-nuts] Anybody have suggestions for time related science fair projects?
On 5/14/18 1:00 PM, ed breya wrote: I don't know what sort of scientific level this contest is geared for, but would guess that for middle-school level, extreme numbers-oriented analysis of esoteric, time-nutty things may not dazzle, but bore the participants, judges, and audience. Even at the middle school level, science fairs can be quite competitive - The California Science Fair draws hundreds of projects at that grade level (Grade 6-9) selected from fairs at the county level, which in turn draw from school fairs. The standard of judging is quite rigorous - a "demo" won't generally be competitive at the state level, although it could make it through the county level - depending on the county. It may be best to relate to more hands-on, everyday experience and observations of "normal" people. I like the suggestions about GPS and stroboscopic and lasery stuff, where one can maybe appreciate how modern everyday things work (like GPS, or how it's possible to talk to or send a picture to anyone in the world on your cell phone, and how these could not happen without precise time), or something visual and physical. Virtually all science fairs prohibit lasers in a display - too many "bad things" happening with remarkably high powered lasers available online. You'll need to show it cannot be operated, or that it cannot present a hazard (i.e. if it's built into a piece of hardware that cannot be modified on site to allow exposure). Even laser pointers are not allowed (because how is the display review committee to know whether it's 1 mW or 100 mW) Some of the props should be "ordinary" things, like the a cell phone or GPS receiver, for example. Lasers are always good as long as there's a direct visual component to the observation. Strobe type stuff is particularly easy, because it's doable with mechanical and acoustical props, and signal measurement times are in reach of common lab equipment like generators, scopes, and counters, and of course there's a big visual experience component. Small power visible lasers are common nowadays, so easy to use. Strobe lights are fairly common too, but maybe not so much as the other items. You can build (or buy) quite a nice strobe light nowadays using high-powered LEDs - the kind used for replacing incandescent and other illumination. This is quite easy and much safer than dealing with flash tubes, and is much more versatile. In fact, maybe this could even be a science fair project. The time element is in the stroboscopic effects and ability to slow or freeze apparent motion - almost everyone has observed this and can relate. A strobe is a fine display, and there's probably interesting time-nuts kinds of experiments one can do using it - the combination of a short duration strobe with a modern cellphone camera running at, say, 240 fps, might be a good way to instrumentally measure a mechanical vibration. But you need to have some set of experiments designed to confirm or reject a hypothesis. You could have a hypothesis about synchronization of vibrating rods on a common base, for instance. ___ 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.
Re: [time-nuts] Anybody have suggestions for time related science fair projects?
Ah. The falling water goes up illusion. https://www.youtube.com/watch?v=GBtHeR-hY9Y -Original Message- From: time-nuts On Behalf Of ed breya Sent: Monday, May 14, 2018 2:01 PM To: time-nuts@febo.com Subject: Re: [time-nuts] Anybody have suggestions for time related science fair projects? I don't know what sort of scientific level this contest is geared for, but would guess that for middle-school level, extreme numbers-oriented analysis of esoteric, time-nutty things may not dazzle, but bore the participants, judges, and audience. It may be best to relate to more hands-on, everyday experience and observations of "normal" people. I like the suggestions about GPS and stroboscopic and lasery stuff, where one can maybe appreciate how modern everyday things work (like GPS, or how it's possible to talk to or send a picture to anyone in the world on your cell phone, and how these could not happen without precise time), or something visual and physical. Some of the props should be "ordinary" things, like the a cell phone or GPS receiver, for example. Lasers are always good as long as there's a direct visual component to the observation. Strobe type stuff is particularly easy, because it's doable with mechanical and acoustical props, and signal measurement times are in reach of common lab equipment like generators, scopes, and counters, and of course there's a big visual experience component. Small power visible lasers are common nowadays, so easy to use. Strobe lights are fairly common too, but maybe not so much as the other items. You can build (or buy) quite a nice strobe light nowadays using high-powered LEDs - the kind used for replacing incandescent and other illumination. This is quite easy and much safer than dealing with flash tubes, and is much more versatile. In fact, maybe this could even be a science fair project. The time element is in the stroboscopic effects and ability to slow or freeze apparent motion - almost everyone has observed this and can relate. Ed ___ 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. ___ 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.
Re: [time-nuts] Anybody have suggestions for time related science fair projects?
I don't know what sort of scientific level this contest is geared for, but would guess that for middle-school level, extreme numbers-oriented analysis of esoteric, time-nutty things may not dazzle, but bore the participants, judges, and audience. It may be best to relate to more hands-on, everyday experience and observations of "normal" people. I like the suggestions about GPS and stroboscopic and lasery stuff, where one can maybe appreciate how modern everyday things work (like GPS, or how it's possible to talk to or send a picture to anyone in the world on your cell phone, and how these could not happen without precise time), or something visual and physical. Some of the props should be "ordinary" things, like the a cell phone or GPS receiver, for example. Lasers are always good as long as there's a direct visual component to the observation. Strobe type stuff is particularly easy, because it's doable with mechanical and acoustical props, and signal measurement times are in reach of common lab equipment like generators, scopes, and counters, and of course there's a big visual experience component. Small power visible lasers are common nowadays, so easy to use. Strobe lights are fairly common too, but maybe not so much as the other items. You can build (or buy) quite a nice strobe light nowadays using high-powered LEDs - the kind used for replacing incandescent and other illumination. This is quite easy and much safer than dealing with flash tubes, and is much more versatile. In fact, maybe this could even be a science fair project. The time element is in the stroboscopic effects and ability to slow or freeze apparent motion - almost everyone has observed this and can relate. Ed ___ 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.
Re: [time-nuts] Anybody have suggestions for time related science fair projects?
What I remember was a brown or black disc with holes around the perimeter. I remember a lot of holes. This was around 1991 or so. -Original Message- From: time-nuts On Behalf Of Bruce Griffiths Sent: Saturday, May 12, 2018 4:39 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Anybody have suggestions for time related science fair projects? Like this so called star target?: https://www.edmundoptics.com/test-targets/resolution-test-targets/1-black-1-white-glass-star-target-5deg-wedge-pair-angle/ Bruce > On 13 May 2018 at 02:45 Bob kb8tq wrote: > > > Hi > > > > > On May 12, 2018, at 7:01 AM, jimlux wrote: > > > > On 5/11/18 9:08 PM, Jeff Woolsey wrote: > >> David.vanhorn wrote: > >>> Measuring the speed of light (Fizeau or Michelson method? Other > >>> ways) > >>> > >>> > >>> I saw a great demo of this at the Exploratorium in SF. They had a long > >>> spool of fiber optic, a disc with holes, and a light source. When > >>> static, if the light shines through the hole in the disc into the fiber, > >>> then you can see the light coming out the other end of the fiber through > >>> a different hole. When rotating, you increase speed and the fiber > >>> output gets dimmer and dimmer till it's gone. At that point, the light > >>> going into the fiber arrives when the other end is blocked, and vice > >>> versa. High tech, but simple. > >>> > >> My favorite exhibit that we never see anymore. IIRC it was a quarter > >> mile of fiber and a green laser. And ISTR that the disc had one > >> hole on one arm and two radially on the other, but I can't remember > >> why. I thought that the light would pass through the same hole > >> twice, once on the way in and on the way out when that same hole > >> rotated 180 degrees to the other end of the fiber. The disk spun > >> somewhere around 50 rps (60 with an AC motor?). > > > > > > 1km in free space would be 6 microseconds round trip. I'm not sure a disk > > spinning at 3600 rpm would work. you'd need to have the "hole spacing" be > > on the order of 6 microseconds - and at 100 rps (6000 RPM), 10 ms/rev, > > you'd need the sending and receiving hole 6/1 of a rev apart (about 0.2 > > degrees). > > > > if you had 10 km of fiber, it would be a bit easier. > > I think the term “long fiber” in this case should really be “very very > long”. Exactly how the typical student funds the acquisition of something in > the “many miles” range, I have no idea. > > You could use an optical grating of some sort as your “spinning disk”. > The end of the fiber is going to be mighty small. The spacing on the grating > could be quite tight. Where you get a circular part like that …. > again no idea. > > Bob > > > > ___ > > 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. > > ___ > 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. ___ 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. ___ 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.
Re: [time-nuts] Anybody have suggestions for time related science fair projects?
On 5/12/18 5:01 PM, Adrian Godwin wrote: How about a demonstration of how GPS works, substituting sound waves for radio ? Maybe three sound sources with harmonically-related frequencies, then measure their phase difference on an oscilloscope. Cheat a bit : you don't need to do cdma acquisition. Have one reference at a low frequency, switch two more on alternately at a higher frequency. Measure the phase difference between one pair at a time and calculate your location relative to the stationary sources. In science fairs that are judged, the rubric really demands something that can be cast into the classic "literature search, hypothesis, experiment, data reduction, conclusion" form. Even straight up engineering is sometimes knocked down - the International Fair (being held this week, as it happens) does have separate rubric for engineering projects. So what you want to do is cast this as an experiment or engineering project. For the latter: "Performance characterization of acoustic multilateration" For a more "sciencey" approach, you'd postulate some theory/hypothesis: "air temperature measurement can be used to compensate for speed of sound variation in acoustic multilateration" ___ 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.
Re: [time-nuts] Anybody have suggestions for time related science fair projects?
Hi: Here's some great ideas from Clifford Stoll: https://www.ted.com/talks/clifford_stoll_on_everything?language=en The transcript is available in 27 languages. PS He has an on line business selling Klein Bottles (some with calibration certificates:) http://www.kleinbottle.com/ I got a Chinese Spouting Bowl from him. http://www.prc68.com/I/ChineseSpoutingBowl.shtml -- Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html ___ 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.
Re: [time-nuts] Anybody have suggestions for time related science fair projects?
Using a pendulum to measure gravity requires precision timekeeping. Wikipedia has a nice discussion of this at https://en.wikipedia.org/wiki/Pendulum#Gravity_measurement There are number of very clever techniques developed long ago, such as Henry Kater's design for a reversible, dual pivot pendulum that made it possible to get quite precise measurements starting about the 1820s. Then, around 1835 Friedrich Bessel found ways to simplify calibration of Kater's design and even cancel out errors due to air drag. More interestingly, gravity measuring pendulums became not of the earliest ways used to standardize the measure of length, which shows how nearly all efforts at standardization ultimately rely on accurate timekeeping. Wayne ___ 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.
Re: [time-nuts] Anybody have suggestions for time related science fair projects?
At telecom wavelengths GDD can be quite low. Laser source spectral widths can also be low. At visible wavelengths an fiber length imbalance of 1m with a 1nm bandwidth light source makes interferometry impossible/difficult without GDD compensation even if delays are matched. The moodulation bandwidth isnt an issue for this application but with a long enough fiber the source spectral bandwidth may be. Polarisation locked single transverse mode VCSELs are inexpensive and typically have spectral bandwidths of 100MHz or so. Bruce > On 13 May 2018 at 11:31 Dana Whitlow wrote: > > > Indeed; however, with single mode fiber the limit is not too bad. At > Arecibo we routinely ran bandwidths in > excess of 1 GHz through fibers of about 1500 ft length with no problems. > For the science fair project a > bandwidth of a few MHz should suffice for lengths of, say, 500 ft. It's > just that I don't know how bad the > multimode dispersion problem would be when using shorter wavelengths, and > I'm sure not equipped to > make any measurements at home now that I'm retired and far away from the > observatory. > > Dana > > > On Sat, May 12, 2018 at 5:44 PM, Bruce Griffiths > wrote: > > > Even with single mode fiber its finite group delay dispersion will likely > > restrict the usable light source bandwidth. > > > > Bruce > > > On 13 May 2018 at 03:38 Dana Whitlow wrote: > > > > > > > > > It may be that a nicely-written request to Corning could yield the loan > > of > > > a big spool of fiber > > > for the duration of a science fair project. > > > > > > Another alternative, perhaps easier to implement, might be an > > > electrically-driven light modulator > > > at the detector end. For the source, an LED or diode laser is easy to > > > modulate at respectable > > > rates. This approach should allow use of such high frequencies that an > > > open optical path using > > > mirrors might even suffice. > > > > > > Or here's an intermediate scheme: > > > If one were to use two modulated sources (or one with a beamsplitter), > > with > > > one path delayed > > > by the long(ish) fiber and the other by a minimal-length local fiber, > > > something resembling a streak > > > camera (implemented with a rotating mirror) might permit use of > > > substantially higher pulse rates > > > than with a rotating disk, without incurring the need for anything very > > > fancy in the way of mechanics. > > > Only the modulated source should require a reasonably accurate drive > > > frequency- the "detector" > > > would be essentially self-calibrating. A small mirror, say of cm size, > > > could probably be safely > > > rotated at Dremel speeds approaching 500 rev/s, and if 1 mrad angular > > > resolution is attained, > > > this would yield a resolution of ~160 ns. So a fiber length of 500 ft > > > (approx 750 ns one-way delay) > > > should yield an angular separation of nearly five "dots" between delayed > > > and undelayed dots. > > > And if the sources are modulated at a rate such that a few pulse > > > repetitions are visible in the > > > field of view, the scheme is self-calibrating as long as the PRF and the > > > velocity factor in the fiber > > > are known. Probably the only precision work would be the optics required > > > to focus a reasonable > > > amount of light from the source(s) onto the two fibers., and I believe > > this > > > requirement could be > > > adequately met with microscope objectives borrowed from one's school's > > > biology lab. > > > > > > A fly in the ointment is that if ordinary (read, inexpensive) IR fiber is > > > used at convenient visible > > > wavelengths, propagation will occur in more than one spatial mode, with > > > different modes propagating > > > at different speeds. I don't know how much of a problem this would > > > raise. But it may be that if > > > tweaking of the transmitting end illumination is done, both in angle and > > > transverse position, most > > > of the propagating light could be confined to a single mode. I speak of > > > visible wavelengths simply > > > because using these avoids the cost of electronic detectors, > > oscilloscopes, > > > etc, potentially saving > > > a lot on the cost of the experiment as well as making for a more > > satisfying > > > presentation. > > > > > > Dana > > > > > > > > > On Sat, May 12, 2018 at 9:45 AM, Bob kb8tq wrote: > > > > > > > Hi > > > > > > > > > > > > > > > > > On May 12, 2018, at 7:01 AM, jimlux wrote: > > > > > > > > > > On 5/11/18 9:08 PM, Jeff Woolsey wrote: > > > > >> David.vanhorn wrote: > > > > >>> Measuring the speed of light (Fizeau or Michelson method? Other > > ways) > > > > >>> > > > > >>> > > > > >>> I saw a great demo of this at the Exploratorium in SF. They had a > > > > long spool of fiber optic, a disc with holes, and a light source. When > > > > static, if the light shines through the hole in the disc into the > > fiber, > > > > then you can see the light coming out the other end of the fiber > > through a >
Re: [time-nuts] Anybody have suggestions for time related science fair projects?
How about a demonstration of how GPS works, substituting sound waves for radio ? Maybe three sound sources with harmonically-related frequencies, then measure their phase difference on an oscilloscope. Cheat a bit : you don't need to do cdma acquisition. Have one reference at a low frequency, switch two more on alternately at a higher frequency. Measure the phase difference between one pair at a time and calculate your location relative to the stationary sources. On Sun, May 13, 2018 at 12:31 AM, Dana Whitlow wrote: > Indeed; however, with single mode fiber the limit is not too bad. At > Arecibo we routinely ran bandwidths in > excess of 1 GHz through fibers of about 1500 ft length with no problems. > For the science fair project a > bandwidth of a few MHz should suffice for lengths of, say, 500 ft. It's > just that I don't know how bad the > multimode dispersion problem would be when using shorter wavelengths, and > I'm sure not equipped to > make any measurements at home now that I'm retired and far away from the > observatory. > > Dana > > > On Sat, May 12, 2018 at 5:44 PM, Bruce Griffiths < > bruce.griffi...@xtra.co.nz > > wrote: > > > Even with single mode fiber its finite group delay dispersion will likely > > restrict the usable light source bandwidth. > > > > Bruce > > > On 13 May 2018 at 03:38 Dana Whitlow wrote: > > > > > > > > > It may be that a nicely-written request to Corning could yield the > loan > > of > > > a big spool of fiber > > > for the duration of a science fair project. > > > > > > Another alternative, perhaps easier to implement, might be an > > > electrically-driven light modulator > > > at the detector end. For the source, an LED or diode laser is easy to > > > modulate at respectable > > > rates. This approach should allow use of such high frequencies that an > > > open optical path using > > > mirrors might even suffice. > > > > > > Or here's an intermediate scheme: > > > If one were to use two modulated sources (or one with a beamsplitter), > > with > > > one path delayed > > > by the long(ish) fiber and the other by a minimal-length local fiber, > > > something resembling a streak > > > camera (implemented with a rotating mirror) might permit use of > > > substantially higher pulse rates > > > than with a rotating disk, without incurring the need for anything very > > > fancy in the way of mechanics. > > > Only the modulated source should require a reasonably accurate drive > > > frequency- the "detector" > > > would be essentially self-calibrating. A small mirror, say of cm size, > > > could probably be safely > > > rotated at Dremel speeds approaching 500 rev/s, and if 1 mrad angular > > > resolution is attained, > > > this would yield a resolution of ~160 ns. So a fiber length of 500 ft > > > (approx 750 ns one-way delay) > > > should yield an angular separation of nearly five "dots" between > delayed > > > and undelayed dots. > > > And if the sources are modulated at a rate such that a few pulse > > > repetitions are visible in the > > > field of view, the scheme is self-calibrating as long as the PRF and > the > > > velocity factor in the fiber > > > are known. Probably the only precision work would be the optics > required > > > to focus a reasonable > > > amount of light from the source(s) onto the two fibers., and I believe > > this > > > requirement could be > > > adequately met with microscope objectives borrowed from one's school's > > > biology lab. > > > > > > A fly in the ointment is that if ordinary (read, inexpensive) IR fiber > is > > > used at convenient visible > > > wavelengths, propagation will occur in more than one spatial mode, with > > > different modes propagating > > > at different speeds. I don't know how much of a problem this would > > > raise. But it may be that if > > > tweaking of the transmitting end illumination is done, both in angle > and > > > transverse position, most > > > of the propagating light could be confined to a single mode. I speak > of > > > visible wavelengths simply > > > because using these avoids the cost of electronic detectors, > > oscilloscopes, > > > etc, potentially saving > > > a lot on the cost of the experiment as well as making for a more > > satisfying > > > presentation. > > > > > > Dana > > > > > > > > > On Sat, May 12, 2018 at 9:45 AM, Bob kb8tq wrote: > > > > > > > Hi > > > > > > > > > > > > > > > > > On May 12, 2018, at 7:01 AM, jimlux wrote: > > > > > > > > > > On 5/11/18 9:08 PM, Jeff Woolsey wrote: > > > > >> David.vanhorn wrote: > > > > >>> Measuring the speed of light (Fizeau or Michelson method? Other > > ways) > > > > >>> > > > > >>> > > > > >>> I saw a great demo of this at the Exploratorium in SF. They had > a > > > > long spool of fiber optic, a disc with holes, and a light source. > When > > > > static, if the light shines through the hole in the disc into the > > fiber, > > > > then you can see the light coming out the other end of the fiber > > through a > > > > different
Re: [time-nuts] Anybody have suggestions for time related science fair projects?
Indeed; however, with single mode fiber the limit is not too bad. At Arecibo we routinely ran bandwidths in excess of 1 GHz through fibers of about 1500 ft length with no problems. For the science fair project a bandwidth of a few MHz should suffice for lengths of, say, 500 ft. It's just that I don't know how bad the multimode dispersion problem would be when using shorter wavelengths, and I'm sure not equipped to make any measurements at home now that I'm retired and far away from the observatory. Dana On Sat, May 12, 2018 at 5:44 PM, Bruce Griffiths wrote: > Even with single mode fiber its finite group delay dispersion will likely > restrict the usable light source bandwidth. > > Bruce > > On 13 May 2018 at 03:38 Dana Whitlow wrote: > > > > > > It may be that a nicely-written request to Corning could yield the loan > of > > a big spool of fiber > > for the duration of a science fair project. > > > > Another alternative, perhaps easier to implement, might be an > > electrically-driven light modulator > > at the detector end. For the source, an LED or diode laser is easy to > > modulate at respectable > > rates. This approach should allow use of such high frequencies that an > > open optical path using > > mirrors might even suffice. > > > > Or here's an intermediate scheme: > > If one were to use two modulated sources (or one with a beamsplitter), > with > > one path delayed > > by the long(ish) fiber and the other by a minimal-length local fiber, > > something resembling a streak > > camera (implemented with a rotating mirror) might permit use of > > substantially higher pulse rates > > than with a rotating disk, without incurring the need for anything very > > fancy in the way of mechanics. > > Only the modulated source should require a reasonably accurate drive > > frequency- the "detector" > > would be essentially self-calibrating. A small mirror, say of cm size, > > could probably be safely > > rotated at Dremel speeds approaching 500 rev/s, and if 1 mrad angular > > resolution is attained, > > this would yield a resolution of ~160 ns. So a fiber length of 500 ft > > (approx 750 ns one-way delay) > > should yield an angular separation of nearly five "dots" between delayed > > and undelayed dots. > > And if the sources are modulated at a rate such that a few pulse > > repetitions are visible in the > > field of view, the scheme is self-calibrating as long as the PRF and the > > velocity factor in the fiber > > are known. Probably the only precision work would be the optics required > > to focus a reasonable > > amount of light from the source(s) onto the two fibers., and I believe > this > > requirement could be > > adequately met with microscope objectives borrowed from one's school's > > biology lab. > > > > A fly in the ointment is that if ordinary (read, inexpensive) IR fiber is > > used at convenient visible > > wavelengths, propagation will occur in more than one spatial mode, with > > different modes propagating > > at different speeds. I don't know how much of a problem this would > > raise. But it may be that if > > tweaking of the transmitting end illumination is done, both in angle and > > transverse position, most > > of the propagating light could be confined to a single mode. I speak of > > visible wavelengths simply > > because using these avoids the cost of electronic detectors, > oscilloscopes, > > etc, potentially saving > > a lot on the cost of the experiment as well as making for a more > satisfying > > presentation. > > > > Dana > > > > > > On Sat, May 12, 2018 at 9:45 AM, Bob kb8tq wrote: > > > > > Hi > > > > > > > > > > > > > On May 12, 2018, at 7:01 AM, jimlux wrote: > > > > > > > > On 5/11/18 9:08 PM, Jeff Woolsey wrote: > > > >> David.vanhorn wrote: > > > >>> Measuring the speed of light (Fizeau or Michelson method? Other > ways) > > > >>> > > > >>> > > > >>> I saw a great demo of this at the Exploratorium in SF. They had a > > > long spool of fiber optic, a disc with holes, and a light source. When > > > static, if the light shines through the hole in the disc into the > fiber, > > > then you can see the light coming out the other end of the fiber > through a > > > different hole. When rotating, you increase speed and the fiber > output > > > gets dimmer and dimmer till it's gone. At that point, the light going > > > into the fiber arrives when the other end is blocked, and vice versa. > High > > > tech, but simple. > > > >>> > > > >> My favorite exhibit that we never see anymore. IIRC it was a > quarter > > > >> mile of fiber and a green laser. And ISTR that the disc had one > hole on > > > >> one arm and two radially on the other, but I can't remember why. I > > > >> thought that the light would pass through the same hole twice, once > on > > > >> the way in and on the way out when that same hole rotated 180 > degrees to > > > >> the other end of the fiber. The disk spun somewhere around 50 rps > (60 > > > >> with an AC motor?). > > > > > > >
Re: [time-nuts] Anybody have suggestions for time related science fair projects?
Would it be too simple a project to have a GPS demonstration: * GPS time, leap seconds (need for) * UTC time * Local Time Zone time (rise, set, noon) * Solar Time (rise, set, noon) * Solid Earth Tides * and a custom sun dial, marked for solar time and local time (a lamp can simulate solar noon and other angles) ___ 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.
Re: [time-nuts] Anybody have suggestions for time related science fair projects?
Even with single mode fiber its finite group delay dispersion will likely restrict the usable light source bandwidth. Bruce > On 13 May 2018 at 03:38 Dana Whitlow wrote: > > > It may be that a nicely-written request to Corning could yield the loan of > a big spool of fiber > for the duration of a science fair project. > > Another alternative, perhaps easier to implement, might be an > electrically-driven light modulator > at the detector end. For the source, an LED or diode laser is easy to > modulate at respectable > rates. This approach should allow use of such high frequencies that an > open optical path using > mirrors might even suffice. > > Or here's an intermediate scheme: > If one were to use two modulated sources (or one with a beamsplitter), with > one path delayed > by the long(ish) fiber and the other by a minimal-length local fiber, > something resembling a streak > camera (implemented with a rotating mirror) might permit use of > substantially higher pulse rates > than with a rotating disk, without incurring the need for anything very > fancy in the way of mechanics. > Only the modulated source should require a reasonably accurate drive > frequency- the "detector" > would be essentially self-calibrating. A small mirror, say of cm size, > could probably be safely > rotated at Dremel speeds approaching 500 rev/s, and if 1 mrad angular > resolution is attained, > this would yield a resolution of ~160 ns. So a fiber length of 500 ft > (approx 750 ns one-way delay) > should yield an angular separation of nearly five "dots" between delayed > and undelayed dots. > And if the sources are modulated at a rate such that a few pulse > repetitions are visible in the > field of view, the scheme is self-calibrating as long as the PRF and the > velocity factor in the fiber > are known. Probably the only precision work would be the optics required > to focus a reasonable > amount of light from the source(s) onto the two fibers., and I believe this > requirement could be > adequately met with microscope objectives borrowed from one's school's > biology lab. > > A fly in the ointment is that if ordinary (read, inexpensive) IR fiber is > used at convenient visible > wavelengths, propagation will occur in more than one spatial mode, with > different modes propagating > at different speeds. I don't know how much of a problem this would > raise. But it may be that if > tweaking of the transmitting end illumination is done, both in angle and > transverse position, most > of the propagating light could be confined to a single mode. I speak of > visible wavelengths simply > because using these avoids the cost of electronic detectors, oscilloscopes, > etc, potentially saving > a lot on the cost of the experiment as well as making for a more satisfying > presentation. > > Dana > > > On Sat, May 12, 2018 at 9:45 AM, Bob kb8tq wrote: > > > Hi > > > > > > > > > On May 12, 2018, at 7:01 AM, jimlux wrote: > > > > > > On 5/11/18 9:08 PM, Jeff Woolsey wrote: > > >> David.vanhorn wrote: > > >>> Measuring the speed of light (Fizeau or Michelson method? Other ways) > > >>> > > >>> > > >>> I saw a great demo of this at the Exploratorium in SF. They had a > > long spool of fiber optic, a disc with holes, and a light source. When > > static, if the light shines through the hole in the disc into the fiber, > > then you can see the light coming out the other end of the fiber through a > > different hole. When rotating, you increase speed and the fiber output > > gets dimmer and dimmer till it's gone. At that point, the light going > > into the fiber arrives when the other end is blocked, and vice versa. High > > tech, but simple. > > >>> > > >> My favorite exhibit that we never see anymore. IIRC it was a quarter > > >> mile of fiber and a green laser. And ISTR that the disc had one hole on > > >> one arm and two radially on the other, but I can't remember why. I > > >> thought that the light would pass through the same hole twice, once on > > >> the way in and on the way out when that same hole rotated 180 degrees to > > >> the other end of the fiber. The disk spun somewhere around 50 rps (60 > > >> with an AC motor?). > > > > > > > > > 1km in free space would be 6 microseconds round trip. I'm not sure a > > disk spinning at 3600 rpm would work. you'd need to have the "hole > > spacing" be on the order of 6 microseconds - and at 100 rps (6000 RPM), 10 > > ms/rev, you'd need the sending and receiving hole 6/1 of a rev apart > > (about 0.2 degrees). > > > > > > if you had 10 km of fiber, it would be a bit easier. > > > > I think the term “long fiber” in this case should really be “very very > > long”. Exactly how the typical student > > funds the acquisition of something in the “many miles” range, I have no > > idea. > > > > You could use an optical grating of some sort as your “spinning disk”. The > > end of the fiber is going to be > > mighty small. The spacing on the grating could be quite t
Re: [time-nuts] Anybody have suggestions for time related science fair projects?
Like this so called star target?: https://www.edmundoptics.com/test-targets/resolution-test-targets/1-black-1-white-glass-star-target-5deg-wedge-pair-angle/ Bruce > On 13 May 2018 at 02:45 Bob kb8tq wrote: > > > Hi > > > > > On May 12, 2018, at 7:01 AM, jimlux wrote: > > > > On 5/11/18 9:08 PM, Jeff Woolsey wrote: > >> David.vanhorn wrote: > >>> Measuring the speed of light (Fizeau or Michelson method? Other ways) > >>> > >>> > >>> I saw a great demo of this at the Exploratorium in SF. They had a long > >>> spool of fiber optic, a disc with holes, and a light source. When > >>> static, if the light shines through the hole in the disc into the fiber, > >>> then you can see the light coming out the other end of the fiber through > >>> a different hole. When rotating, you increase speed and the fiber > >>> output gets dimmer and dimmer till it's gone. At that point, the light > >>> going into the fiber arrives when the other end is blocked, and vice > >>> versa. High tech, but simple. > >>> > >> My favorite exhibit that we never see anymore. IIRC it was a quarter > >> mile of fiber and a green laser. And ISTR that the disc had one hole on > >> one arm and two radially on the other, but I can't remember why. I > >> thought that the light would pass through the same hole twice, once on > >> the way in and on the way out when that same hole rotated 180 degrees to > >> the other end of the fiber. The disk spun somewhere around 50 rps (60 > >> with an AC motor?). > > > > > > 1km in free space would be 6 microseconds round trip. I'm not sure a disk > > spinning at 3600 rpm would work. you'd need to have the "hole spacing" be > > on the order of 6 microseconds - and at 100 rps (6000 RPM), 10 ms/rev, > > you'd need the sending and receiving hole 6/1 of a rev apart (about 0.2 > > degrees). > > > > if you had 10 km of fiber, it would be a bit easier. > > I think the term “long fiber” in this case should really be “very very long”. > Exactly how the typical student > funds the acquisition of something in the “many miles” range, I have no idea. > > You could use an optical grating of some sort as your “spinning disk”. The > end of the fiber is going to be > mighty small. The spacing on the grating could be quite tight. Where you get > a circular part like that …. > again no idea. > > Bob > > > > ___ > > 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. > > ___ > 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. ___ 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.
Re: [time-nuts] Anybody have suggestions for time related science fair projects?
It may be that a nicely-written request to Corning could yield the loan of a big spool of fiber for the duration of a science fair project. Another alternative, perhaps easier to implement, might be an electrically-driven light modulator at the detector end. For the source, an LED or diode laser is easy to modulate at respectable rates. This approach should allow use of such high frequencies that an open optical path using mirrors might even suffice. Or here's an intermediate scheme: If one were to use two modulated sources (or one with a beamsplitter), with one path delayed by the long(ish) fiber and the other by a minimal-length local fiber, something resembling a streak camera (implemented with a rotating mirror) might permit use of substantially higher pulse rates than with a rotating disk, without incurring the need for anything very fancy in the way of mechanics. Only the modulated source should require a reasonably accurate drive frequency- the "detector" would be essentially self-calibrating. A small mirror, say of cm size, could probably be safely rotated at Dremel speeds approaching 500 rev/s, and if 1 mrad angular resolution is attained, this would yield a resolution of ~160 ns. So a fiber length of 500 ft (approx 750 ns one-way delay) should yield an angular separation of nearly five "dots" between delayed and undelayed dots. And if the sources are modulated at a rate such that a few pulse repetitions are visible in the field of view, the scheme is self-calibrating as long as the PRF and the velocity factor in the fiber are known. Probably the only precision work would be the optics required to focus a reasonable amount of light from the source(s) onto the two fibers., and I believe this requirement could be adequately met with microscope objectives borrowed from one's school's biology lab. A fly in the ointment is that if ordinary (read, inexpensive) IR fiber is used at convenient visible wavelengths, propagation will occur in more than one spatial mode, with different modes propagating at different speeds. I don't know how much of a problem this would raise. But it may be that if tweaking of the transmitting end illumination is done, both in angle and transverse position, most of the propagating light could be confined to a single mode. I speak of visible wavelengths simply because using these avoids the cost of electronic detectors, oscilloscopes, etc, potentially saving a lot on the cost of the experiment as well as making for a more satisfying presentation. Dana On Sat, May 12, 2018 at 9:45 AM, Bob kb8tq wrote: > Hi > > > > > On May 12, 2018, at 7:01 AM, jimlux wrote: > > > > On 5/11/18 9:08 PM, Jeff Woolsey wrote: > >> David.vanhorn wrote: > >>> Measuring the speed of light (Fizeau or Michelson method? Other ways) > >>> > >>> > >>> I saw a great demo of this at the Exploratorium in SF. They had a > long spool of fiber optic, a disc with holes, and a light source. When > static, if the light shines through the hole in the disc into the fiber, > then you can see the light coming out the other end of the fiber through a > different hole. When rotating, you increase speed and the fiber output > gets dimmer and dimmer till it's gone. At that point, the light going > into the fiber arrives when the other end is blocked, and vice versa. High > tech, but simple. > >>> > >> My favorite exhibit that we never see anymore. IIRC it was a quarter > >> mile of fiber and a green laser. And ISTR that the disc had one hole on > >> one arm and two radially on the other, but I can't remember why. I > >> thought that the light would pass through the same hole twice, once on > >> the way in and on the way out when that same hole rotated 180 degrees to > >> the other end of the fiber. The disk spun somewhere around 50 rps (60 > >> with an AC motor?). > > > > > > 1km in free space would be 6 microseconds round trip. I'm not sure a > disk spinning at 3600 rpm would work. you'd need to have the "hole > spacing" be on the order of 6 microseconds - and at 100 rps (6000 RPM), 10 > ms/rev, you'd need the sending and receiving hole 6/1 of a rev apart > (about 0.2 degrees). > > > > if you had 10 km of fiber, it would be a bit easier. > > I think the term “long fiber” in this case should really be “very very > long”. Exactly how the typical student > funds the acquisition of something in the “many miles” range, I have no > idea. > > You could use an optical grating of some sort as your “spinning disk”. The > end of the fiber is going to be > mighty small. The spacing on the grating could be quite tight. Where you > get a circular part like that …. > again no idea. > > Bob > > > > ___ > > 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. > > ___ > time-nuts mailing list -- time-nuts
Re: [time-nuts] Anybody have suggestions for time related science fair projects?
How about a Stroboscope? - Mike B. Feher, N4FS 89 Arnold Blvd. Howell NJ 07731 848-245-9115 ___ 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.
Re: [time-nuts] Anybody have suggestions for time related science fair projects?
Hi > On May 12, 2018, at 7:01 AM, jimlux wrote: > > On 5/11/18 9:08 PM, Jeff Woolsey wrote: >> David.vanhorn wrote: >>> Measuring the speed of light (Fizeau or Michelson method? Other ways) >>> >>> >>> I saw a great demo of this at the Exploratorium in SF. They had a long >>> spool of fiber optic, a disc with holes, and a light source. When static, >>> if the light shines through the hole in the disc into the fiber, then you >>> can see the light coming out the other end of the fiber through a different >>> hole. When rotating, you increase speed and the fiber output gets dimmer >>> and dimmer till it's gone. At that point, the light going into the fiber >>> arrives when the other end is blocked, and vice versa. High tech, but >>> simple. >>> >> My favorite exhibit that we never see anymore. IIRC it was a quarter >> mile of fiber and a green laser. And ISTR that the disc had one hole on >> one arm and two radially on the other, but I can't remember why. I >> thought that the light would pass through the same hole twice, once on >> the way in and on the way out when that same hole rotated 180 degrees to >> the other end of the fiber. The disk spun somewhere around 50 rps (60 >> with an AC motor?). > > > 1km in free space would be 6 microseconds round trip. I'm not sure a disk > spinning at 3600 rpm would work. you'd need to have the "hole spacing" be on > the order of 6 microseconds - and at 100 rps (6000 RPM), 10 ms/rev, you'd > need the sending and receiving hole 6/1 of a rev apart (about 0.2 > degrees). > > if you had 10 km of fiber, it would be a bit easier. I think the term “long fiber” in this case should really be “very very long”. Exactly how the typical student funds the acquisition of something in the “many miles” range, I have no idea. You could use an optical grating of some sort as your “spinning disk”. The end of the fiber is going to be mighty small. The spacing on the grating could be quite tight. Where you get a circular part like that …. again no idea. Bob > ___ > 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. ___ 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.
Re: [time-nuts] Anybody have suggestions for time related science fair projects?
On 5/11/18 9:08 PM, Jeff Woolsey wrote: David.vanhorn wrote: Measuring the speed of light (Fizeau or Michelson method? Other ways) I saw a great demo of this at the Exploratorium in SF. They had a long spool of fiber optic, a disc with holes, and a light source. When static, if the light shines through the hole in the disc into the fiber, then you can see the light coming out the other end of the fiber through a different hole. When rotating, you increase speed and the fiber output gets dimmer and dimmer till it's gone. At that point, the light going into the fiber arrives when the other end is blocked, and vice versa. High tech, but simple. My favorite exhibit that we never see anymore. IIRC it was a quarter mile of fiber and a green laser. And ISTR that the disc had one hole on one arm and two radially on the other, but I can't remember why. I thought that the light would pass through the same hole twice, once on the way in and on the way out when that same hole rotated 180 degrees to the other end of the fiber. The disk spun somewhere around 50 rps (60 with an AC motor?). 1km in free space would be 6 microseconds round trip. I'm not sure a disk spinning at 3600 rpm would work. you'd need to have the "hole spacing" be on the order of 6 microseconds - and at 100 rps (6000 RPM), 10 ms/rev, you'd need the sending and receiving hole 6/1 of a rev apart (about 0.2 degrees). if you had 10 km of fiber, it would be a bit easier. ___ 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.
Re: [time-nuts] Anybody have suggestions for time related science fair projects?
David.vanhorn wrote:
> Measuring the speed of light (Fizeau or Michelson method? Other ways)
>
>
> I saw a great demo of this at the Exploratorium in SF. They had a long spool
> of fiber optic, a disc with holes, and a light source. When static, if the
> light shines through the hole in the disc into the fiber, then you can see
> the light coming out the other end of the fiber through a different hole.
> When rotating, you increase speed and the fiber output gets dimmer and dimmer
> till it's gone. At that point, the light going into the fiber arrives when
> the other end is blocked, and vice versa. High tech, but simple.
>
My favorite exhibit that we never see anymore. IIRC it was a quarter
mile of fiber and a green laser. And ISTR that the disc had one hole on
one arm and two radially on the other, but I can't remember why. I
thought that the light would pass through the same hole twice, once on
the way in and on the way out when that same hole rotated 180 degrees to
the other end of the fiber. The disk spun somewhere around 50 rps (60
with an AC motor?).
--
Jeff Woolsey {{woolsey,jlw}@jlw,first.last@{gmail,jlw}}.com
Nature abhors straight antennas, clean lenses, and empty storage.
"Delete! Delete! OK!" -Dr. Bronner on disk space management
Card-sorting, Joel. -Crow on solitaire
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Re: [time-nuts] Anybody have suggestions for time related science fair projects?
On 5/11/18 7:07 AM, Philip Gladstone wrote: On 11/05/2018 07:23, jimlux wrote: On 5/10/18 9:55 PM, Hal Murray wrote: A few months ago, I was a judge for the county level middle school science fair. (I'm not very good at what they wanted, but that's a different problem.) What sort of interesting time related experiments can a middle school geek do? Borrowing serious gear may not be off scale as long as a youngster can run it. The whole area of celestial nav is time related and uses very simple equipment - Telling time by measuring the sun in some way. Occultation of stars by the moon. Positions of jupiter's big 4 moons. Pendulum experiments. If the student has a way to change their altitude, can they measure changes in g. Driving a pendulum. Coupled resonators (spring/mass, pendulum, vibrating rods) Measuring the speed of light (Fizeau or Michelson method? Other ways) Water clock, sand hour glass, etc. Measuring performance variation over environmental variations. the trick with good science projects is finding something that's not just a "lab demo" - where there's some engineering component to figuring out how to execute the demo with unusual or improvised equipment, or where you're measuring something that's not been done before. The advice that we got when doing a middle school science project was that you wanted an experiment with only one variable (altitude or temperature etc) and a measurement of a single variable (maybe over time). and with multiple measurements possible - most middle school projects tend to be a "one and done" - you get big kudos if you show even basic statistical analysis - a simple significance test is a big deal, assuming you're not doing it with some cookbook calculator. You'd need to be able to explain what it means to the judges. And something where you show an appreciation of measurement precision and any curve fit. I used to mark down projects where they used Excel to do a regression curve, and then reported the coefficients with 5 digits of precision, on measurements with at most 2 digits. (and no, not thousands of measurements to get a sqrt(N) improvement) AVAR is a kind of sophisticated concept - I think it would be hard for a middle schooler to adequately explain what it is (heck, there's enough trouble for people who do it for a living). ___ 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.
Re: [time-nuts] Anybody have suggestions for time related science fair projects?
How about measuring variations in propagation delay for WWV on various frequencies, or WWVB, using GPS ticks as a reference. DanaK8YUM On Fri, May 11, 2018 at 9:41 AM, Van Horn, David < david.vanh...@backcountryaccess.com> wrote: > > Measuring the speed of light (Fizeau or Michelson method? Other ways) > > > I saw a great demo of this at the Exploratorium in SF. They had a long > spool of fiber optic, a disc with holes, and a light source. When static, > if the light shines through the hole in the disc into the fiber, then you > can see the light coming out the other end of the fiber through a different > hole. When rotating, you increase speed and the fiber output gets dimmer > and dimmer till it's gone. At that point, the light going into the fiber > arrives when the other end is blocked, and vice versa. High tech, but > simple. > ___ > 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. > ___ 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.
Re: [time-nuts] Anybody have suggestions for time related science fair projects?
Measuring the speed of light (Fizeau or Michelson method? Other ways) I saw a great demo of this at the Exploratorium in SF. They had a long spool of fiber optic, a disc with holes, and a light source. When static, if the light shines through the hole in the disc into the fiber, then you can see the light coming out the other end of the fiber through a different hole. When rotating, you increase speed and the fiber output gets dimmer and dimmer till it's gone. At that point, the light going into the fiber arrives when the other end is blocked, and vice versa. High tech, but simple. ___ 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.
Re: [time-nuts] Anybody have suggestions for time related science fair projects?
On 11/05/2018 07:23, jimlux wrote: On 5/10/18 9:55 PM, Hal Murray wrote: A few months ago, I was a judge for the county level middle school science fair. (I'm not very good at what they wanted, but that's a different problem.) What sort of interesting time related experiments can a middle school geek do? Borrowing serious gear may not be off scale as long as a youngster can run it. The whole area of celestial nav is time related and uses very simple equipment - Telling time by measuring the sun in some way. Occultation of stars by the moon. Positions of jupiter's big 4 moons. Pendulum experiments. If the student has a way to change their altitude, can they measure changes in g. Driving a pendulum. Coupled resonators (spring/mass, pendulum, vibrating rods) Measuring the speed of light (Fizeau or Michelson method? Other ways) Water clock, sand hour glass, etc. Measuring performance variation over environmental variations. the trick with good science projects is finding something that's not just a "lab demo" - where there's some engineering component to figuring out how to execute the demo with unusual or improvised equipment, or where you're measuring something that's not been done before. The advice that we got when doing a middle school science project was that you wanted an experiment with only one variable (altitude or temperature etc) and a measurement of a single variable (maybe over time). Philip ___ 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.
Re: [time-nuts] Anybody have suggestions for time related science fair projects?
Hi NTP time offsets through various phases of the distribution process ….. Bob > On May 11, 2018, at 12:55 AM, Hal Murray wrote: > > > A few months ago, I was a judge for the county level middle school science > fair. (I'm not very good at what they wanted, but that's a different > problem.) > > What sort of interesting time related experiments can a middle school geek do? > > Borrowing serious gear may not be off scale as long as a youngster can run it. > > - > > An alternat meaning to the "nut" part of time-nuts: ") > https://www.snopes.com/fact-check/schools-removing-analog-clocks/ > > > -- > These are my opinions. I hate spam. > > > > ___ > 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. ___ 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.
Re: [time-nuts] Anybody have suggestions for time related science fair projects?
On 5/10/18 9:55 PM, Hal Murray wrote: A few months ago, I was a judge for the county level middle school science fair. (I'm not very good at what they wanted, but that's a different problem.) What sort of interesting time related experiments can a middle school geek do? Borrowing serious gear may not be off scale as long as a youngster can run it. The whole area of celestial nav is time related and uses very simple equipment - Telling time by measuring the sun in some way. Occultation of stars by the moon. Positions of jupiter's big 4 moons. Pendulum experiments. If the student has a way to change their altitude, can they measure changes in g. Driving a pendulum. Coupled resonators (spring/mass, pendulum, vibrating rods) Measuring the speed of light (Fizeau or Michelson method? Other ways) Water clock, sand hour glass, etc. Measuring performance variation over environmental variations. the trick with good science projects is finding something that's not just a "lab demo" - where there's some engineering component to figuring out how to execute the demo with unusual or improvised equipment, or where you're measuring something that's not been done before. For instance, measuring time with Jupiter's moons has been done for centuries, but has it been done by taking cell phone pictures through a telescope and then measuring the distances on the resulting images? Can you make a sundial with a webcam pointed at a spherical reflector (to make an "all-sky camera") Other experiments play off a old joke - there's one about "how to you tell how tall a building is using a barometer" - take it to the top of the building drop it, and time how long it takes til it hits the ground. Build a pendulum the height of the building, using the barometer as a pendulum bob. Characterizing a clock is a good one - a) there's well developed analytical tools for doing the data reduction (AVAR, etc.) b) the experiment lends itself to collecting multiple data sets from multiple instances of the clock in question c) clock performance is affected by environment, so there's lots of potential experiments. ___ 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.
[time-nuts] Anybody have suggestions for time related science fair projects?
A few months ago, I was a judge for the county level middle school science fair. (I'm not very good at what they wanted, but that's a different problem.) What sort of interesting time related experiments can a middle school geek do? Borrowing serious gear may not be off scale as long as a youngster can run it. - An alternat meaning to the "nut" part of time-nuts: ") https://www.snopes.com/fact-check/schools-removing-analog-clocks/ -- These are my opinions. I hate spam. ___ 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.
