How does light diffraction work? Learn with lasers and human hair

Are you a fan of cool science experiments? Alvaro, a physicist from the Omni Calculator team, shows you how to measure the width of a human hair using nothing more than a handy online calculator and... the power of lasers!

To learn more visit the Hair diffraction calculator:

Discover our 1400+ calculators at and never do maths by hand again!

0:00 Introduction
1:04 Experiment showcase
3:09 Explaining diffraction
8:00 Validating the results
10:24 Summary

Channel logo design: Farhan Khan
Quality control: Natalia Nazim, Farhan Khan, Reina Sagnip, and Mateusz Mucha
Host, Writer, Shooter, Editor: Alvaro Diez
Wave interference animation:
Original source: Acoustics and Vibration Animations - Dan Russell, Grad. Prog. Acoustics, Penn State
Intro animation music:
Song: Dojokratos - Towel Defence Jingle Loose
Music provided by FMA (Free Music Archive)
Background Music
Song: Valcos & Chris Linton - Without You [NCS Release]
Music provided by NoCopyrightSounds
Free Download/Stream:

46 komentarze:

Aleksandra Zając
Aleksandra Zając:
had I seen this in high school, i'd be signing up for physics immediately :D thanks for the great video, keep making more!
Such a brilliant experiment! Please upload more experiment videos!
Mrs. L
Mrs. L:
Definitely the red one :3 I loved the video and the Star Wars references! As a little minus - I could see that you're not looking straight into the camera all the time. The rest was neat, keep it going!
Steve Wooding
Steve Wooding:
Hey, I loved this video. You definitely explained the topic well and made me understand it. Your style is nice and simplistic and makes the video more entertaining. Looking forward to more videos!
This is really cool! When you say waves, do you also mean ocean waves, can they form constructively and destructively as well?
Wojciech S
Wojciech S:
Nice channel, very cool stuff. I'm planning to do this experiment at home.
Bogna H.
Bogna H.:
Really cool first video, take some validation
Maciek N.
Maciek N.:
I like how easily you explain all of this. More interesting than my physics lessons! :)
Lila Pl
Lila Pl:
wow! that's probably the first time I managed to understand anything from physics. Really cool! Want more :)
Kenneth Alambra
Kenneth Alambra:
I used to play with laser pointers and diffraction gratings and flat lenses like the lenticular lens and Fresnel lenses to kinda create holographic projections onto the wall or through a fog or smoke. But this is something new to me. This is a great experiment and I would love to try this to see wire thicknesses just for the fun of it! 😄 More of this, please!
Dude I use your calculators to figure out accurate scales in some of my videos. Thanks for the great service!
Physics Online
Physics Online:
This is a great video - and so well explained. I'd never thought of getting students to measure the width of their hair like this before.
Hanna .P
Hanna .P:
Super explanatory video! Congrats for making this topic easy ;)
Mateusz Mucha
Mateusz Mucha:
Now I know something I hadn't known before. Thanks, Alvaro!
Katarzyna Mucha
Katarzyna Mucha:
What else can we measure with lasers?
Dominika Miszewska
Dominika Miszewska:
This used to be one whole chapter in my textbook back in school...  I finally understood the thing in just 10 min
Alnis Smidchens
Alnis Smidchens:
Awesome video! I love how it tied together a physics explanation with a practical experiment that is really easy to do. I can't wait for more!
Darek Walczy-Antkowicz
Darek Walczy-Antkowicz:
I really like how rough and genuine it is. Pretty great 1st video.
Magdalena Plewniak
Magdalena Plewniak:
Hey! You are great physics' explainer. Enjoyed it a lot
Elem Oghenekaro
Elem Oghenekaro:
I'll try to measure the thickness of a piece of paper with what I've learnt here... hmm, should be fun 😅
. Amazing video!
Mohammed Motaz
Mohammed Motaz:
I like your calculator sites dude, a lot of types and live answers. good job
awesome! I d loved to do this experiment in the science fair.
Julia Ż.
Julia Ż.:
Can't wait to try this at home!! Thanks for sharing the materials
Joanna Michałowska
Joanna Michałowska:
This is sooooo cool! Can't wait for the next video!
Maciej Kowalski
Maciej Kowalski:
Such a brilliant experiment! Please upload more experiment videos!
Rohith Narra
Rohith Narra:
Amazing intro to wave particle duality!
Pretty Beetch
Pretty Beetch:
Wow, so science can be fun. Good to know ;) Thanks for that video.
Will be more on this channel regular videos like that?
Cute experiment, but I won't give you bonus points until you adjust for the 3d shape of the hair and the variance in the index of diffraction near the edge of the hair, or at least the non-zero k-space distribution from your laser ;)

Pretty sweet video though. DM me on reddit next time you try and get feedback on one, I'll try and be more detailed on production stuff.
Emma G
Emma G:
Great job! (: Super interesting.
Grzegorz Łyczak
Grzegorz Łyczak:
Brilliant video, thank you for explanation <3
You're awesome and i like and usually use Omni calculators in many fields
Al Gepé
Al Gepé:
8:46 I got scared 😅
Nice video, the idea is very cool!
Nice video! I like your sense of humor :D
Des Cuddlebat
Des Cuddlebat:
Found the calculator while doing some Dyson sphere math, ended up here learning about diffraction, 10/10 would click "sure" again
Andre Oka
Andre Oka:
Bro, you got beautiful eyes.
craving Attention
craving Attention:
"they give this pop of colour to our parties..." ...parties :( RIP parties [*]
YRN Steve
YRN Steve:
your page helped me understand planck's constant and photon energy. Nice experiment here, i came from a pop-up ad on your page
Damn, that's a lot of calculator for one website!
Raya McGuire
Raya McGuire:
This is so helpful
C A Holmes
C A Holmes:
Great! love lasers
Rejhan Kavazbasic
Rejhan Kavazbasic:
Great video!
Maja Plewniak
Maja Plewniak:
Ale fajoooo! Nic nie rozumiem :( ale widzę. Like it!
Nice video! :)
Jeremy Guo
Jeremy Guo:
came from reddit lol and this is a great video
Eddie Warren
Eddie Warren:
lit vid dude
Sean Leith
Sean Leith:
What I learned from this video: it is not pleasant listen to someone speak with accent. Normally, I wouldn't to watch this video for more than 10 seconds, but need someone explain the diffraction.