How to find the speed of light (Fizeau experiment)
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- Опубликовано: 7 мар 2020
- In 1849 a French scientist, Hippolyte Fizeau came up with an ingenious method to measure speed of light.
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Good job! It's cool that you're focusing on the experiment, not on the history like other videos.
This is based on the presumption that light travels the same speed in all directions!!!! Here is why this is NOT provable:
Why The Speed Of Light Is Unmeasurable
ruclips.net/video/pTn6Ewhb27k/видео.html
Yes
@SzymonMajewski history is just for inspiration and motivation if you have both then comes experiment
Really 🤔🤔
bot
Great finally someone who focuses on the details of the experiments and develops the calculations and not only on the history of the experiment.
This is a great video, very educational. I loved the 3d render!!! You are very good at this. Please continue making content! I'd love to see you as one of the main educational channels on yt.
This is a great depiction of the experiment! I had heard about this, but it was nicely spelled out here. Thanks!!
i hope you make more. this kind of videos has so much potential!
Wow, excellent video. This is one of the best visualizations of Fizeau I’ve ever seen. Thank you!
Nice! I’ve heard about this experiment many times in the histories of science but they hardly ever or never go into the details of how it was done. Great video!
I dont think its practical in the example because even if you used a laser pointer with very low beam divergence (say 0.5milliradian), the spot size becomes 8m in radius after travelling the 16km mentioned here (16km*0.5mrad=8m). You'd need to decrease the distance, make it rotate a lot faster and make the teeth sufficiently large that it blocks the spot after the beam is diverged.
But he did do it somehow, so I think I'm wrong in what I said above
@@miron__ in original experiment i dont think they had lasers and they were 8.6km apart
Great visual animation and modern way to determine the speed of C. Interesting side note, it was in 1676 Danish astronomer Ole Roemer determined that light has speed and was not too far off by observing the difference in time of the appearance of Io coming out from behind Jupiter as being either 8 minutes early or 8 minutes late, depending on where earth was in relationship to Jupiter. When earth was farther away on the opposite side of the sun it was late, when it was on the same side of the sun as Jupiter (much closer) it was early. He was off by approximately 1/4 in his speed calculations based on an incorrect assumption of the distance earth was from the sun. It still amazes be that it could be determined with that close of accuracy nearly 350 years ago!
Only 2.4k view ....you deserves millions
Awesome , thank you for that clear explanation.
This is based on the presumption that light travels the same speed in all directions!!!! Here is why this is NOT provable:
Why The Speed Of Light Is Unmeasurable
ruclips.net/video/pTn6Ewhb27k/видео.html
Thank you for this awesome video.I hope you will keep doing interesting videos like this one.
This is a cool animation and explanation but if the regular mirror was actually positioned like this the light would reflect off it and way over the rest of the apparatus. It needs to be tilting downward to reflect the light back to the cog. Angle of incidence = angel of reflection.
I searched for a video like this from so many days .I finally got a good video.keep it up.Try to make more videos.Urs way of explanation and animations are perfect.My suggestion is whatever ur situation work a little hard.May u'll get better responses ....
This is based on the presumption that light travels the same speed in all directions!!!! Here is why this is NOT provable:
Why The Speed Of Light Is Unmeasurable
ruclips.net/video/pTn6Ewhb27k/видео.html
Excellent demonstration. To the point and exact.
very good animation and a fullcomplete explanation with the calculation
This assumes light travels at the same speed in both directions.
It is not assumption it is for abovious because it is seen from laws of reflection that angle of incidence is equal to angle of reflection
Yes, we all saw the veritasium video 😄😄
Perfectly explained! great work 😍
Actually, this is not how you measure the speed of light. It's how you measure the 'round trip speed of light'. We can't yet tell if light travels faster in certain directions and slower in others.
Beautiful explanation!
Thank you so much,
Please upload more scientific videos like this..
Excellent video, very precise to illustrate the calculation of the speed of light.
Thank you for the animation and amazing explanation!
Very nice channel! Instant subscriber. Keep going, it will grow fast soon.
good video, the animation really helped!
Just make more videos, you are explaining very well. Thank you!
Marvelous graphics and explanation.we expect more
hands down the best explanation of this experiment i've ever seen
Thank you this was so useful!
excellent work, thanks for this.
Very good animation and explanation.
I was hoping you would explain how the light source worked. The beam has to be bright enough and collimated enough to still be visible at a distance of over 16 km. I assume this was the main barrier to performing an experiment like this before Fizeau. After all, the precision-made gear and adjustable rate of rotation were figured out by clockmakers centuries earlier. And semi-glazed glass had existed for quite a while (though I don't know how well they worked as beam splitters).
the lamp was a regular gas lamp. his apparatus was a very clever tabletop device -- a telescope with the eye piece separated from the body of the telescope, with the cogged wheel and a beam-splitter in between. the telescope is BOTH acting as a collimated light projector and receiver. light is projected out from the telescope, to the mirror, back to the telescope [eg you are looking at your own reflection on a distant mirror, through a telescope which itself is projecting light outward]. the beamsplitter/light src arrangement is kinda similar to a modern front-projecting microscope or optometrist's ophthalmoscope. the margin for error would be small but aligning the mirror would not be very hard because you basically have to just roughly set the mirror, then 'find the spot where you see your own reflection through the telescope' then put the device there.
It must have been tedious to get the return mirror adjusted. I mean, how did he communicate with his helper 8 km away? A corner cube and a laser would have helped!@@PplsChampion
im guessing, but i think it was semaphores + something like 'lets both look at eachother through 2 telescopes, then once we both see the other, one of us will set a mirror to reflect the image at their eyepiece back up the telescope towards the other'. the second telescope is the aligned retroreflector. @@randydewees7338
@@PplsChampion I was wondering if he used an arc lamp, but it seems you're right, it was just "a lamp," presumably a gas streetlight (since an oil lamp couldn't get bright enough). I'm surprised he could even see it over a 17 km distance.
@@randydewees7338 Easy. They could've used a light source + morse code. Put your hand in front of the light source = no light = 0(.). Remove your hand = light = 1(_).
Fantastic illustration
Please do more video like thia
Great video, keep that content
A simple solution to a very complex question , mathematics is fun to work with.
Excellent explanation! I 've finally understood the function of the toothed wheel. Brilliant vid! Thanks 😃
Great work man
awesome video, great explanation and diagram. I really enjoy the way you pronounce tooth
Beautiful explanation, and immaculate derivation. I now fully understand this experiment, as a former math minor.
Thanks ayuta team it really helped me a lot :)
Nice job bro, great video!
Now that the speed of light is fundamental constant used to define the metre, the output from this experiment is actually an accurate measure of the distance to the mirror.
Thanks for the video explaining process 😊
Great video! Would you also consider animating Foucault’s experiment?
Very good explanation.
Thanks
Wonderful, wonderful video
What a brilliant experiment.
Well done awesome explanation ❤
Wow man! amazing video!
Sweet! Can’t wait to test this on my 4 mile laser setup from Christmas
Great video.
In 1849..... Where was this 800 meter experiment set up...?
What was a strong enough source of light...?
How was the cog rotated at precise and constant speed....?
What instrument was used to record time in 10,000ths of a second..?
This is great! Thank you!
Great explanation!
Your eyes is camera that captures in limit frame per second . So the limitation is from the Eyes not from the light I mean when you see the light stop blinking that mean your Eyes stop distinguish . Example if you see helicopter in the movie you will see the fan is always turning or slower turning and that related to the camera used limited frame per second not to other parameter. I am not convinced with such experiment. But thanks you have the best explain
Thank You , really helped.
Well explained sir
Thanks for sharing..
Very helpful Sir
Good explanation i love your teaching
Great explanation thanks a lot i subscribed
Great explanation.
I have heard descriptions of this experiment but it was never made clear that the 1:59 total length of the light path was 16 km. I had always thought it was done in the lab which woul require the wheel to be rotating at several thousand rpm.
We need more of this kind of education! Science is super fun when you understand it!
excellent and an easy explanation
This channel is underrated
Very good, friend. Clear and clever. I understand it. 👍👍👍🇪🇦🇪🇦🇪🇦
It was very helpful thank you
Great great video!
wow that's extremely clever
Please make more videos like this
great explanation
So good, thanks
Well done
Nice job bro.
I have searching for long to get the clear understanding on measuring speed of light. Thank you for this explaination
doesnt travel the same speed in both directions.your taking an average here
Woooow! It's a brilliant explanation with simple Math.
First time I completely understand an experiment about speed of light. I should have born in the 19th century but having this RUclips channel at home.
amazing video
Too much underrated channel
Very informative
Thank you!
This raised more questions than it answered.
What kind of light did they use in the 19th century to be able to shine it 8km and back? (One thing is power, and yet another is how they kept the narrow beam on that distance)
How did they measure the exact rotation speed?
Good questions! This experiment was done on two large hill tops (8 km apart ~ 5 miles) in the middle of the night. Without streetlights and a moonless sky, it would be dark enough to see a focused candle a that distance. It must have taken some precision work and patience with lenses and mirrors to align the whole thing though. And no, it does not need to be a tightly focused beam. They were only concerned with the light that passed through the gear.
Measuring the speed of the cog would be no harder than measuring the gears of a spring-wound clock (invented in 14th century). They were pretty accurate for the day.
Galileo tried this experiment centuries before with just a handheld lantern. He concluded that light is way too fast to measure, or it COULD be instantaneous as many scientists of the day thought.
Also, the 8km ~ 5 mile limit is due to the Earth's curve. Any farther and you would need a taller hill. :)
Also, the speed of light was roughly calculated in the late 1600's by observing delays in Jupiter's moon orbits. This gear experiment was no random guess. They were basing the gears, distances, and rotation speeds off prior knowledge (and a few hunches).
Was wondering the same thing. This experiment may be right theretically, but i would like to see it done for real... How many lights can shrine 8 km x2?
grt idealogy behind finding the speed of light ..thanks for the vedio
😮😮😮well information good show 😅
Really helpful tq sm
*For information*
Speed of light is a *constant*
More understanble than the mirror experiment. Its really hard to imagine with that one.
Genius experiment.
Nice explanation, but to be strict, it shows only how the average speed of the light is when traveled back and forth to the mirror. It is in principle impossible to measure the speed of the light without assuming that the speed is the same in both directions.
Something that I've noticed about speed of light measurements is that it seems like it can't account for 2 things.
1 is relativity. Even though these are stupidly small distances and relativistic effects are going to be mad small, it still exists especially for things moving at the speed of light (aka light itself) also like you said we have no way of verifying the 2 way speed of light. It could be effected by things like refection.
Also going back to the relativistic stuff. Something I never quite understood was how they apparently got around that problem by using a mirror. The idea is that you can't 2 seperate emitter. And reciever. Because relativity is going to skew your results due to the distance between the two objects. So to not have this happen you have the emitter and reciever be on the same device abd just bounce the light back from a mirror.
The issue I find myself contemplating is.. how is that any different? Like yeah the light technically starts I'm the same place it ends up but the measurement is taking place between the mirror, and the reciever. How does that not functionally operate as if the emitter was just were the mirror was, because if it does then any problem youed have from having seperate emitters amd recievers is going to also be present when using a mirror set up.
very helpful
Super clever thank u
this is awesome
Thank You..Very conceptual….
Too lazy to go 8000 metres to try this
SO COOL!!!
Amazing' idea to determine speed of light.
Can I ask you what software are you using for the animation and the 3D models?
the original experiment didnt require the light to be fully blocked, but partially was enough
Exactly to the point....no extra bakwaas 👍 great
Beautiful
We take the efforts of scientist for granted
awesome bro