How to find the speed of light (Fizeau experiment)

In 1849 a French scientist, Hippolyte Fizeau came up with an ingenious method to measure speed of light.

[MrSzymixx]

Good job! It's cool that you're focusing on the experiment, not on the history like other videos.

[aryanjohnson]

Too lazy to go 8000 metres to try this

[benjaminalcantar]

Great finally someone who focuses on the details of the experiments and develops the calculations and not only on the history of the experiment.

[badcodehash]

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.

[danielpearce]

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.

[reshmagkstudy]

Only 2.4k view ....you deserves millions

[GrantOakes]

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!

[memesalad]

That's the two-way speed of light.
the two-way speed of light may not be the one-way speed of light, and we'll never know

[may]

In 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..?

[nash.hawkins]

Great video! Would you also consider animating Foucault’s experiment?

[ScienceBoy]

This is a great depiction of the experiment! I had heard about this, but it was nicely spelled out here. Thanks!!

[orkunasc]

Awesome, thank you for that clear explanation.

[samialsakka]

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

[JunnyorMedeiros]

Light has a different speed according to the environment.
Light speed is not a constant,
Gravity affect the speed of light,
Also oxygen particles affect it's speed
slowing it down,
We've only measured it here on earth affected by Gravity and gas molecules.
Out of space, in a perfect vacuum, without gravity, in one way direction, light travels much more faster because it has no barrier.
It also means that 14 billions light years away galaxies are been measured wrong, light does not take that long to reach us, we are receiving it's light much more faster, so the age of the universe are also being dated wrong.

[manognyanimishkavi]

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 ....

[jonchicoine]

this sounds more theoretical, no? also, the video show the light hitting the mirror at an angle and then returning on the same path ...

[EebstertheGreat]

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).

[willo]

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!

[djquick]

This assumes light travels at the same speed in both directions.

[lekunberriko]

Very good, friend. Clear and clever. I understand it. 👍👍👍🇪🇦🇪🇦🇪🇦