Amplitude, period, frequency and wavelength of periodic waves | Physics | Khan Academy

[@AB-fm7qh]

@9:57, velocity is equal to *displacement* over time, not distance over time. This is a very small but important distinction just as a reminder to those watching! Distance traveled over time is related to speed, which is a scalar quantity. Displacement over time is related to velocity, which is a vector quantity.

[@reyza3640]

Thanks

[@jimmyti9cer]

I love how he repeats stuff as he writes it. I dont know why but it helps for some reason.

[@shubhamg9495]

Also nice for visually challenged people (just in case) or if anyone is watching in low quality in poor data connection.

[@DosHDable]

Heard ''jerking up and down '' automatically came to check comments

[@devindrarambo3293]

same hahahaa

[@sujeewa8067]

dammit, same here man! :D

[@laava1028]

lmao same

[@lykith7058]

Same here lol

[@alyoshadiaz4283]

Thank u wish I had u as my science teacher!!

[@abdullah374]

Are u still using this account?

[@925LY]

I wonder how many times Sal has said "Magenta" over the years

[@debidattamishra8677]

A lot

[@robindraramnarine6068]

i have finals tomorrow an i didnt understand this until i watched your video thanks

[@sukantpanigrahi76]

How are you going to give a exam the next day after newly learning just the basic formulae for waves that you could read in a book? What grade are you in btw.

[@sukantpanigrahi76]

An*

[@sukantpanigrahi76]

oh. well glad to see you want to learn. work hard!

[@d7mi4eve]

dude i learnt a whole chapter hours before the midterm and i got 24/25 even though the test was extremely hard

[@danielaramirez676]

digital learning days gang😗✌🏼

[@bakumhaku6454]

Hi

[@dtdark212]

This helped me for trigonometric graphs. couldnt thank you enough!

[@Tron1992]

Sal, I think you're reading my mind! It is just the lesson I wanted you to upload!

[@qazzyy]

80% of the people watching have either an exam or test in the next few days

[@btdpro752]

Qaz if you have an exam or test use the notes you got from school your teachers gave you ways to study and also helped you comprehend in class

[@annettemilburn4336]

Tomorrow

[@d7mi4eve]

well.. not me

[@jasonyu5508]

Me 1 hour and 15 mins

[@mintbrownieangelfish-6114]

Well you're not wrong. I've got a test tomorrow. :)

[@NobleNayen]

Love your videos, I owe you my degree :P

[@dylanbrown4683]

Sal is a truly talented instructor. I've learned so much from him!

[@Hipsterjes]

Corona Virus online school gang.

[@Raina430]

I have been trying to grasp this all of my life. Always bad at math and science ( and I have been alive a longtime), you made this crystal clear. Thanks so much!

[@agricolaterrae]

Oddly, we just reached this lesson in my physics class. Amazing timing.

[@reemoo4kill]

your videos motivate me to study! thanks :D

[@cynthuquita]

that's so true! i want to study hahaha

[@soomindaroosianguy]

this is saving my life for my physics quiz on thursday; everybody should donate to this channel

[@nadirmarikkar4335]

I ALSO DIDN'T UNDERSTAND ANYTHING ABOUT WAVES UNTIL I WATCH PREVIOUS AND THIS VIDEOS .THANKS A LOT.....REALLY IT'S VERY HELPFUL.ONCE AGAIN THANK YOU VERY MUCH ..

[@matamax7342]

These videos honestly make me wonder why I need school I could literally just learn everything from KZbin

[@AmasaTony81947]

I had the good fortune to have Richard Feynman as a teacher at Cal Poly. I also was taught by Sir Ronald Syme at Christchurch. The sheer presence of such scholars could never be equaled by a You Tube video. The atmosphere of deep respect for learning and the intellect can’t be matched by a video, nor can the camaraderie and sense of shared purpose. Finally I met my wife in graduate school.She was a distinguished scholar in the Classics dept. whose nickname (unknown to her) was the goddess. The You Tube community hath not her like!

[@KevinTong1]

@@AmasaTony81947 you are really ignorant to assume that every lecturer is as passionate as Richard Feynman and that everyone is as fortunate you are.

[@athiyah1]

14 years old up in Singapore, if your'e in a private school like mine (School of Science and Technology, Singapore). Most likely the mainstreaming academic schools learn this at the age of 15. May I remind you that Singaporeans only start learning physics at the age of 13. If your'e wondering what I learn for science before the age of 13, its just simple science foundations to help us cope in secondary school.

[@blueli9ht101]

finally after 6 years i know what is that mean ,, the first thing i will do when i get my first paid i will denote to this academy

[@misctutorials1468]

"Maybe i'm doing it every two seconds"

[@srsly4789]

💀👍

[@lychee159]

love u Sal! tmrw is my physics test and now for the very first time i am over confident lol .

[@JustAnotherFace]

Dude, you are awesome! You explain things so logically and break subjects down in a way I can understand. Thanks!

[@nafisulislam4376]

Always watch videos from this channel.......

[@azizahchesu3313]

will be having the biggest physics examination in my high school this Tuesday and this video helps me a LOT. thankyouu!

[@saimeghana2261]

peak = crest, i guess.

[@devindrarambo3293]

yep could be either one that your accustomed to

[@sukantaraut9269]

Yes

[@nourkandil7650]

Yeah

[@aubreymaryamacalde4279]

Yess

[@Unkoww18383]

Lol I liked how you counted so fast to 20 In 12:18

[@070.ravishashwathj.k.9]

Guy Shapira hifi

[@hernanarias13]

it was hilarious

[@tjli5146]

These videos helps a lot. Thanks!!

[@juliahill3912]

Im in an advanced science class and my teacher told us that we have a test on this after 2 classes of him just giving us chapters to read from the textbook XD. Thanks for helping me understand and i will pass this on to my friends who are also having trouble ( the rest of my class ahah)

[@kelliecliff5914]

THANK YOU SO MUCH!! I have a science project on this and just couldnt understand frequency. This video got me to understand it!! I was so frustrated and freaking out cos i didnt understand! Now I am so much more relaxed!!

[@Hannah-jq9hh]

Can you please do a video on phase change on reflection for light (Where there is a phase change of π on reflection at an interface where there is an increase in optical density, e.g. a higher refractive index such as light going from air to glass. There is no phase change on reflection where there is a decrease in optical density, e.g. a lower refractive index such as light going from glass to air) And explain why that is? Thank you:)

[@AimzIIT]

Literally , From my Bottom of Heart ❤️ Thank You Master Teacher ! This is one the Bestest Explaination I've got since 2 yrs !

[@ad2181]

Sal, Show what happens when the differential impluse (-+) wave reaches the end of the string, different reflection result, if the end of the string is floating (open) or locked down (shorted) . Keep posting, I'm enjoying.

[@ballsolove]

Excellent job breaking this down! Thank you!!

[@MalikisOnline]

May you live long Sal ... I could not clear this concept thought out my life.

[@Belle-wi1pr]

His videos are absolute gold He clarifies everything

[@matty2battie]

Counting to 20 with Sal. 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,19,20.

[@ibbyizaG]

Even though i didn't get any sleep last night, and don't plan to tonight, and even though im stressed like crazy about my AS Physics exam in two days, i still chuckled at 2:20 ^^

[@DaytakTV]

20 people are not meant for STEM.

[@andrewmiller3055]

That was an awesome video. I have never understood frequency and hear it so often. The wave application is really cool.

[@blueworld2740]

Thanks now I'm ready for my test. Good job clearing it out for me.

[@SnuggieGuy]

HOLY SHIT THANKYOU SOOO MUCH!!!, I'm kinda abit behind in my physics class and I need some help figuring out what lambda, velocity, frequency is and stuff thanks alot>

[@monsterjazzlicks]

Because you deal with VELOCITY is this videos examples, should the equations not be solving for DISPLACEMENT rather than DISTANCE? And by the same token, include the DIRECTION of EAST in these cases please? Thanks.

[@pulkitsinha3736]

Displacement and distance...transverse waves, like light, travel in straight lines. And this video covers the basics. So no reflection. Just a straight line. And the velocity in reality is speed here but...people into physics tend to use velocity all the time.

[@monsterjazzlicks]

***** Thanks very much. I will be coming back to these videos in the early new year . . .

[@HotPepperLala]

You should actually do a video on standing waves, nodes, frequencies (or just pull out the topics from AP Physics B)

[@shakarkhan]

wow, this is one your best videos ever! thank you for such a clear explanation.

[@snitox]

The highest point is actually called a crest

[@aeceallia]

Ya, I also got confused there

[@whiteeyedshadow8423]

they are both the same thing, crest and peak

[@Chaosflyex98]

Khan, your vids are great.. they've helped me a ton. But why do you not win some sort of award?!

[@dhiruiitk]

Thank you! It was helpful.

[@chrispierce1418]

Holy crap! I actually understood everything that you said! And the good thing is you didn't bore me to death... A+

[@ChemKage]

All waves are created by Sal and his string because he is god, Thankyou so much SalJesus

[@raptors551]

great video sal, soooo helpful, hopefully itll be enought for my exam

[@PartVIII]

i am just wondering, could you please elaborate on how a wave can move in a vacuum without a medium? Sal does a fantastic job thoroughly covering the material, but his true forte is explaining abstract concepts.

[@xGalasko]

PartVIII it can't lol

[@NoRefundsXD]

OMG, I understood this in class, but Khan Academy never fails to blow my mind even when I think I understand something.

[@myblurryfaceromance5146]

this is actually the most helpful thing of my life thank you so much sal

[@narendhankani5015]

So so so much helpful Please continue making videos We are with u U re doing an awesome job

[@thomasmcdonnell1957]

My physics teacher calls a periodic wave a transversal wave

[@superdude9077]

+Thomas McDonnell Mine too, I'd assume it's interchangeable.

[@clairecui8462]

you should watch his first video in the introduction to waves he talks about transverse/longitudinal (this comment was from 3 years ago but this might help others)

[@ehtishamkhan294]

isnt the peak called a crest ?

[@superdude9077]

+Ehtisham Khan Same thing, different ways of saying it.

[@theslasher6441]

Ehtisham Khan American vs British

[@Sitara04]

could you please do more videos on electrostatics. more examples etc. and also trigonometry, the identities,radians etc

[@brockroper1168]

thanks mate. heaps of help

[@Numh2030]

im following every video on waves and optics :) pleasee keep goin

[@gitarthasarmah3302]

Khan academy is the saviour❤

[@skyeus3837]

this video is very helpful..thanks man

[@ltran96]

Sal, can we please get some Light waves and interference videos? Its really needed.

[@farhanahmed5843]

wow very good way to explain.

[@stevelawrie7087]

excellent, thanks from a Dad!

[@chucklesreadstoyou]

So helpful, for some reason I never learned this s#*% in high school, now I'm caught up.

[@turtlespwnnoobs101]

Thanks man got a physics test tomorrow, saved me.

[@schmiigle]

'hopefully i found that helpful' did you say?? DAMN RIGHT i did, thats equivalent to 3 2hrs physics lessons!!

[@TheCalvinWu]

thank you very much, it is really really help

[@cvtavares10]

great video... excellent way of explaining

[@FrankieSwaggz]

Thank you so much! Great Video!

[@LipService]

The only reason is to get a college certificate for evidence SUPER non-sensical...........I'm learning more from him than all my teachers combined.

[@shubhamrajpurohit4736]

awesome tutorials!!..clear explanation!! :)

[@handlethisnut]

Really good video. Thanx it helps alot

[@marthashelton236]

thankyou, have a science exam next week

[@MIMZification]

this was really helpful thank you

[@MichaelBracewell]

I wish I could like this video more than once.

[@lifeasbrad3260]

yo what program do you use to draw out the lectures ? also, thanks for the help.

[@hypnotistchicken]

omg you are so much better than my my teacher

[@asherif1000]

Thanks Khan you made my life so much easier :) You should build your own school :-)

[@unclesoe7669]

Thanks, Now I can do my work.

[@yousorooo]

Question: If the horizontal axis is time, the period is the "distance" between two peaks, and wavelength is also the distance between two peaks, wouldn't period = wavelength?

[@yousorooo]

Ok I get it now. A wave can't be graphed with a 2D curve, it's a 3D surface _y(x,t) = Asin(ax + bt)_, and period is the distance between two peaks with fixed x and wavelength is the distance between two peaks with fixed t. At any fixed point on the wave with distance _x_ from the origin, the distance between two peaks on the t-y plane is the *period*. At any fixed time t, the distance between two peaks on the x-y plane is the *wavelength*. The two peaks are different.

[@sleepyxyz5]

Thanks a nice brush up for my basics =)

[@fikret8422]

thank you that is absolutely logical

[@nathandrouillard2927]

I really love your videos, thank you

[@darrell5774]

v good ......thankyou

[@harryfung1304]

2:15

[@beep7634]

fufufufu

[@kevinparsley6806]

thats where the peak to trough expression comes from in investing.. interesting.

[@dro04yoo]

thank you. thank you. thank you.

[@nourkandil7650]

Really perfection 💘

[@TristanCorbellari]

Thanks so much, dude!

[@faisalabdi9029]

thanks

[@davidjeon4587]

In this video he states that the period is 1 over the period he has the right idea but a better way to think about periods is the reciprocal method

[@Stmpnqueen]

Thank you!!!

[@MsGreenDayFan1995]

This is quite good but I think your vids should go more into detail..my teacher always gives us really hard homework to do and what you explain in your videos is just not enough to solve them..and im still going to school..im really wondering how this - although the basics are well explained - can help university students...

[@siddheshbirajdar8623]

Thankful

[@ruijiayang980]

displacement means how far it has moved from the original position. consider the first peak as the original position,then the distance to the consecutive peak will be the displacement! @shilpa bhandari

[@pathanmatin996]

Nice good information

[@dnmdogmusic3360]

thank you!