How to Measure Wavelength of Light with a Meter Stick - The Science of Light with Mr. G - Part 2

[@BealsScience]

I almost didn't upload this video because I was worried that it wasn't "entertaining" enough. But, I chose to upload it anyway out of respect for the genius of Mr. G and because I want my students to learn the applications of math and science. So, while this is not a "traditional" Beals Science video, I hope you enjoy it and learn something new! Thanks for watching! Craig

[@BealsScience]

waterrocketsrule organic chemistry includes the organic molecules which contain carbon and C-H bonds. Inorganic covers the rest. So most of the experiments you see are probably inorganic Chemistry related but oftentimes we use organic compounds in the reaction (methane, sugars, etc). So a general chemist doesn’t focus only in one field of Chemistry but is interested in how all things interact and react - all the people you mentioned probably fall in this last category. Thanks for the question!

[@moleculardescriptor]

I am glad you did. It's a perfect video and I love math!

[@justenhansen]

Glad you did!

[@BealsScience]

@@justenhansen thank you!! Me too.

[@MRdoA77]

The intellectuals that your target demographic is does not come for face value entertainment. We seek knowledge plain and simple!

[@RelaxTotal]

Underrated channel!

[@BealsScience]

Thank you!

[@solaokusanya955]

I don't understand that 7:27 part where he said "one travels 1 wavelengths further..

[@vishwajeetjangra3390]

dayum !! never felt this good after learning a topic theoretically but you also get see the real world application.... thanks

[@BealsScience]

Thank you for the kind words!

[@SilviDion]

I was taken to this video from a search engine. This is a very interesting way of calculating the wavelength of visible light. Would you be able to measure the wavelength of invisible light in any way, if you know the source? There are many IR heat lamps on the market, but how do you know it is really infrared light, when the human eye cannot see infrared light? They all look like normal heating lamps painted in red.

[@BealsScience]

You could measure IR but you would need to have an IR laser at one wavelength. You would also need a way to detect it on the wall so you could measure.

[@LoftechUK]

I want to go back to school.... oh I’m knocking on the door of 51 lol

[@BealsScience]

Thank you! I give all the credit to Mr. G! He’s fantastic!!

[@pixxelwizzard]

I couldn't really follow the math, but I followed the concept and I found it super interesting. Thank you for uploading this!

[@BealsScience]

Thanks for watching and commenting!

[@insaneo4430]

Why didnt my geometry teacher teach me math like this? I probably would have learned something and not hated math so much!

[@BealsScience]

I had a similar experience with math. I didn't really appreciate math until I started to dive into science. I had to see the application of math to help it make sense to me! I hope the video helps others see how math/science can make sense of the world!

[@Troeltsch7873]

Actually I would have though that sin theta was the quotient of Lambda divided by the other arm at 5:36 since you can tell from because that one looks like the tipping side of it the most or at least it looked that way first. And then I backed up to slow this down some. Of course Mr. G is right since his perpendicular intersection is stuck on to his tipping side though he goes a little bit faster than I would when he is looking at triangles that may as well have belonged on a flying trapeze and now in retrospect it seems that youtube has some strong advantages over classroom, since, apart from the fact that you can leave out the tuition part of it you can also backup on a youtube. And then Oh yes I get it now that's the sin of the angle, unless if maybe it's the sine of it and actually I forgot that particular detail too.

[@CraigBeals]

@@Troeltsch7873 👍

[@TeamOrdigamer]

That’s awesome! Thank you for sharing!

[@BealsScience]

Thank you for the kind words and thank you for watching!

[@lycakito1814]

This is so cool, great to see... calculating the wavelength of light by hand!

[@BealsScience]

Thank you!

[@itsiwhatitsi]

This is an underrated video. Very interesting 👍

[@BealsScience]

Thank you for the kind words!!

[@glennpeteparinas4829]

Awesome, got my long time question answered!

[@BealsScience]

What was you long time question?

[@glennpeteparinas4829]

@@BealsScience it's funny but I worked as maintenance technician (civilian personnel) on sophisticated military optical equipment like laser guided missile, NVG, infrared, thermal cam, etc so since it has its own test bench to test the optical equipment we didn't bother so much about knowing the theories and those nanometer units they are using. Thank for the overviews, thanks for the upload.

[@BealsScience]

Thank you for watching and commenting!

[@evox786]

Great video! Does this procedure only work with lasers? I'm assuming the light source has to be of a single wavelength. Or could you measure the distance between two matching colors when using white light? Granted, it would be less accurate without having dots to measure from.

[@BealsScience]

Thanks for watching! If you were to use an incandescent flashlight, for example, you would end up with the rainbow of visible colors in a few areas on the board and could compare them. But, as you mentioned, you wouldn’t have a point of light so the measurements would not be quite as accurate.

[@sandramueller2592]

He used a flashlight in the beginning which separated colors. You can use any light source.

[@LoftechUK]

This is awesome

[@odal6770]

Thank you for a very illuminating presentation! But I wonder, how are the gaps in a diffraction pattern measured? Also with light? That would all make it rather a circular argument..?

[@BealsScience]

The gaps are measured by distance (usually lines/cm or lines/mm

[@odal6770]

@@BealsScience yes, but how? When your are talking about 500 lines, 1000 or more per centimeter, how is it done?

[@TheManjusu]

what kind of laser light did you use? where can you buy the diffraction grating and laser light of different color. Thanks.

[@lalski08]

Now i can test the toxic street lamps and take my council to court, thanks for the upload.

[@SoundsLikeOdie]

QUESTION: Can you use a old CD and reflect the laser as opposed using your 1micron refractor slide (I don't have one) Assuming this actually works, would the capacity of the CD make a difference? I assume the spaces between the tracks would be different for a CD and DVD. I have used a CD to see the different wavelength intensities and that is fascinating especially with fluorescent lights. It would be amazing to take that to the next level and do the maths behind it.

[@SoundsLikeOdie]

I did a quick experiment . I grabbed a laser a CD and a DVD. Google says the space between tracks on a CD are 1.6micrometers and 0.74micrometers on a DVD. I targeted the laser on to the disk and looked at the reflection. The DVD has a much wider angle than the CD.

[@SoundsLikeOdie]

HA, IT WORKED!!! I did the following. I placed a Laser measuring meter on my table and pointed it straight up to the ceiling and left it there shining( Measurement was 1588mm). Placed the CD flat next to the Laser meter and shun my hand laser onto the disk so the reflection was next to the Laser meters dot. Then I measured the distance between the meter dot and the refracted dot from my hand laser with a hand tape (750mm) Since google says the tracks on the CD are 1.6um I did the maths and I came up with a angle of 25.28deg and a wavelength of 683nm The sticker on my laser says 630nm to 680nm I consider that a win!! Great Video!!! Thanks for the lesson.

[@BealsScience]

Thank you for all of this information! I love that you took the idea and figured out a way to make it work with a CD!!

[@jugalkishoreroy9985]

This was awesome.. thank you kind sir!

[@BealsScience]

Thanks!!

[@DaveFer]

We taped a thin copper wire across a red lase as a means of reproducing the famous "Double Slit Expreiment", an it was successful -- we saw an interference pattern on the wall. I wonder if this same method could be used in place of the diffraction grating.

[@BealsScience]

That sounds really cool! I would be willing to bet that you could measure wavelength that way!

[@tommycooper1223]

Great video. I love science. This is facinating stuff really and i wish more people would learn and be educated about things like this. Keep it up Beals Science. Mr. G, You're awesome. Thanks for the enightenment. Take care.

[@BealsScience]

Thanks for watching and thank you for the kind words!! I will be sure to share with Mr.G!

[@denielalain5701]

Hi! Why does the little triangle (in the tables right side) have a 90 degree angle?

[@OrinSorinson]

Would a polarising film before the diffraction grating affect the beam separation?

[@BealsScience]

That is a great question! My guess would be yes but I will put a polarizing filter in front and see - I will be getting the lasers and gear out in 2 weeks for some new experiments. I will try to remember to respond with what I find out.

[@OrinSorinson]

@@BealsScience That's great! At this point, intuition doesn't do much, even with understanding some of the principles and phenomena.

[@BealsScience]

Agreed.

[@antilogism]

I just tried my 632.8 nm polarized HeNe laser (a 24 year old 3222H-PC-60) with a 1000 nm film grating. Rotating it seemed to make no difference at all. BTW my measurement was just 0.9 nm longer than the spec so I guess my grating (and tape measure) are good!

[@jimschuyler4339]

Right off I have to chuckle, the description is amusing. Math much like learning almost anything can be known to cause great anxiety.

[@BealsScience]

Math can make people cry! I've seen it...

[@FuriousTortoise]

Great video! Not boring at all. I do have a serious concern though! Most green lasers under $50 (the ones we buy online) are 808nmIR lasers with a component that drops wavelength to 532nmGREEN. Because of this, 808nmIR is most assuredly coming though as well and at 5mW or scary higher since these lasers are often mislabeled to get around US laws. Look into it! Protect your eyes from ANY green laser and even add a IR filter just to be safe!

[@JuiicyComp]

Awesome video! Well put together!

[@BealsScience]

Thank you!!

[@poojasingh1371]

Thanku so much ❤️ Love the way you explained everything n connect it to the practical world . Loved it ❤️

[@BealsScience]

Thank you for the kind words!

[@evilplaguedoctor5158]

Is there a way to do this using a prism rather than a defraction grating?

[@BealsScience]

I am sure a prism would work. You would first need to shine a know. Wavelength through it to calculate the angle of refraction, then use that for unknown lights.

[@ayushthada9544]

Is this method applicable for Radio Waves as well?

[@BealsScience]

Yes!

[@chessur-t5z]

I didn't calculate, but thank you so much for such a good explanation! I appreciate it a lot :) You are great! I was watching this and comparing it to my school lessons and I was really disappointed. Eleven years for what? In the end, I learnt it thanks to two kind guys in youtube.

[@chessur-t5z]

P.S. English is not my native language but I have understood your explanation almost at once when I didn't understand or learn smth from lessons in my native language. I feel sorry for my teachers and such education :(

[@BealsScience]

Thank you for the kind words! I am pleased that you learned something from the video!

[@masterdanprice2904]

Where can I purchase one of those factional degrading lenses. Please advise

[@BealsScience]

You can find a whole selection of them on Amazon which all have different spacing so you can measure different things or get different effects: amzn.to/3HxIU6G I hope that helps!

[@TheMixmastamike1000]

will this work if the light source is not a laser? like a UV light bulb ?

[@BealsScience]

If the UV light is a specific wavelength and you pass it through a slit or point filter, it should work.

[@TheMixmastamike1000]

@@BealsScience awesome! thanks.

[@sasis5533]

Absolutely awesome.. Never such a Vedio.. Real time calculation

[@BealsScience]

I was blown away when he showed me this too!

[@jag353]

Great clip!

[@BealsScience]

Thank you!!

[@raymondgonzales6439]

Awesome!

[@BealsScience]

Thank you!

[@primate3609]

Mr. G

[@BealsScience]

He’s the man!

[@rodolfot8318]

Excellent explanation. Why only 4,045 views? Regards from New Zealand

[@BealsScience]

Thanks!

[@yon8024]

nice vid mate

[@BealsScience]

Thanks!!

[@Tudumanu]

awesome, thx a lot!

[@BealsScience]

Thank you for the kind words!

[@JaiKishoreTheSacredSprit]

Thanks

[@BealsScience]

Thanks for watching!

[@frankhaydon658]

fantastic!

[@BealsScience]

Thanks!

[@GornubiusFlux]

This is so cool

[@BealsScience]

Thank you!!

[@Troeltsch7873]

Well thanks very much for the magic trick which came totally unexpected after a bunch of old schoolbooks on this sort of business where what came a lot easier was an early nineteenth century story with some Thomas Young and his double slit experiment. Constructive and destructive interference, that way. As good as I can guess it what this new teacher has yet demonstrated is that, if the beam is presumably coherent, then, for reasons that have yet to be learned, the very fine grating will separate it into beams that have wavefronts normal to their directions of propagation? Is that it? Anywhere close? I don't think I would vote for this very mysterious stuff in any competition with two slits from Thomas Young as you find him in the Serway School book from 1983, if you had to start out with either one or the other. I'm not too sure whether I might be outvoted on that? And maybe I'm getting it wrong? Or maybe no one had said it was otherwise? But even the nineteenth century stuff is like a wizard of oz since all of these interference talkers have been cooking up pictures that could not have been made out of a commonsense sort of a world to start with. Is it that maybe commonplace light is coherent in general? If maybe that is the case then how did that happen? If it isn't then how did that light become visible? Should incoherent light be like a destructive interference pattern with a zero angular size to it? Is that like neutrino radiation? Or is it that maybe that is what neutrino radiation really is? And coherence? What? If even a nominally monochromic light has some amount of bandwidth then calling it coherent would seem to be stuffing it some. And how could it POSIBLY be coherent? Did everyone else think that the atoms and their various electrons are presumably like a philharmonic orchestra who makes the electromagnetic waves go according to the same conductor all the time and did no one else think that that would be a remarkable state of affairs to say the least? And even if all creation was like a philharmonic orchestra then some basic arithmetic would tell you that the visible light from any stars up there would have to have very fine spectral lines before any coherence could possibly survive a multiplication of errors over those astronomical distances. There are cosmical riddles behind all of this business.

[@BealsScience]

Thanks for the info!

[@coachdonald1082]

This was great! I wish I had gotten engaged in geometry and physics in HS. All the math made sense conceptually but I got lost the moment he said inverse tangent 🤣

[@BealsScience]

I’m with you!

[@crystalzzzzzz5662]

I wonder if there’s a machine that could automatically analyze the wavelength?

[@BealsScience]

Me too!

[@MrVirkMedia]

Wow this should be taught in school

[@BealsScience]

I agree! I was blown away when he taught me this!

[@Sqwince23]

The error may not be your measurement but rather the spacing tolerance of the grating. It may not be exactly 1,000,000/m

[@BealsScience]

Very true! It would be interesting to get grating from several suppliers and see if there is a differenced!

[@justinfong2388]

awesome

[@BealsScience]

Thanks!!

[@IIT24Aspirant]

As an Indian, that math was so basic like a 9th or 10th grader can do while sleeping💀 and thanks for the video, brother🙌

[@BealsScience]

Thanks for watching!!

[@libertarianPinoy]

Im here cause i wanna make sure the UV lamp i buy isnt less than 240nm so it doesnt produce ozone.

[@apexLT]

You can't measure what you can't see :( I'm looking for same UV wave lenght answer.

[@wesbaumguardner8829]

This is actually a calculation based off of a measurement. It is not a measurement in and of itself. With that said, it takes a certain faith that the mathematical proofs of the trigonometric functions are both correct, and directly applicable to this phenomena. As the waves themselves are not directly observable, it is quite a faith, indeed. How do we know that this methodology is not simply an enclosed echo chamber which simply provides systematically incorrect results consistently?

[@therocket39]

Did you know the Meter and imperial were invented at the same time..

[@BealsScience]

I did not know that!

[@pierreuntel1970]

eww math...

[@BealsScience]

That’s one of my favorite Mr. G lines!