James Charbonneau

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@soflarez849 6 күн бұрын

Great explanation!

@Knightslash. 7 күн бұрын

Sir I have some doubts about this , logically speaking writing the displacement equation with dsin(kx+phi) remains the same , but in the wave equation derivation I can't understand how the second equation is used

@Jakery1057 7 күн бұрын

The center of the milkyway looks absolutely chaotic. Stars and debris flying all over the place. It must be hell like.

@WrathfulEnd 9 күн бұрын

I’m really struggling with breaking the wave number into components/vector components for 2d/3d waves… please provide any reference material, a video for this, or if you have already made video for this let me know!!! Excellent video, this made the fundamental concepts make so much more sense

@dhrubokarim8751 16 күн бұрын

I still have a question, though I don't think that in Cambridge AS syllabus we will be getting any question above 5th harmonic in one open end and one closed end but let's say there is a diagram with a large wave with 8 nodes and 9 antinodes, then what will be the number of harmonics here?

@epic_editz_x 20 күн бұрын

Which app r u using?

@JamesCharbonneau 19 күн бұрын

@epic_editz_x Notability. I record using Camtasia.

@theodoreaguglia8902 28 күн бұрын

Some of those stars are moving tens of thousands of miles PER SECOND

@Mike-mb2yx 29 күн бұрын

Great explanation, thanks!

@clems6989 Ай бұрын

How can 1/f (period) = 2pi? When frequency can be anything..?

@gafcs Ай бұрын

It is a nice way of thinking, liked it. I do not know if you can make the field zero at infinity, it can be a constant field, like the infinity charged plate for electric field.

@JamesCharbonneau Ай бұрын

@@gafcs This is a good question and I address it in another comment. As you point out, the mathematical statement is that B_1 and B_2 are the same constant, and that constant is the same value everywhere outside the solenoid, no matter the distance away from the solenoid. Our goal is now to determine that constant. Is it 4 Tesla? 3 Telsa? Some other number? Mathematical reasoning got us here, but now were have to use some physics reasoning. Physics reasoning requires us to think about information the real world and experiments give us. The first thing to note is that there is nothing in the equation that links B_1 to a physical property of the solenoid (i.e., the windings per length, the radius of the solenoid, etc). Changing the features of the solenoid doesn’t change the constant. This is different than the result we get for a charged plane, where the value is linked to a physical quantity of the plate (the surface charge density). In fact, it seems like we are allowed to pick any constant for the B field outside the solenoid we want. The only constant that really makes sense, that doesn’t change with the physical characteristics of the solenoid, is if the field were zero. But, let’s go further. Somewhat troubling is that if we pick any constant other than zero, the energy due to this magnetic field, because it is constant everywhere, is infinity and non zero infinitely far away for the solenoid, but perhaps you might expect that from something infinitely long, like from a charge plane. The last thing is that if we actually build a really long narrow solenoid, we notice that the magnetic field inside can be very strong, and the magnetic field just outside is very closer to zero. This hints that an infinitely long solenoid, which is actually impossible to build, has a magnetic field of zero outside. We use experimental facts and physical reasoning to guide us to the fact it is zero. I hope that helps.

@leishangthemhero827 Ай бұрын

Thanks sir❤❤you did a great job. I wish my professor taught the same way u do.😊

@jacobvandijk6525 Ай бұрын

If you can explain this to me (and you did), then I'm quite certain that you can explain the Aharonov-Bohm effect also to me. No matter the effect of this remark, thanks for explaining the first part anyway. P.S. I realise that this is not within the frame-work of this course.

@ayaan.sayed74638 Ай бұрын

Thanks a lot bro u really helped me with my homework

@JamesCharbonneau Ай бұрын

@@ayaan.sayed74638 Haha, glad to help!

@Leoo___ 2 ай бұрын

underrated. perfectly explained thanks!!

@DaughterofPersephone0630 2 ай бұрын

I just spent 2 hours just to figure out that wavenumber is basically radian per meter This is what happens when your foundational knowledge is wobbly

@OCA8WhitePeopleAreAlbinosOCA8 3 ай бұрын

i knew JESUS wasn't Real 🫨

@monkeyking2685 3 ай бұрын

beautifully explained sir, thank you!

@mambrinox 3 ай бұрын

This "proof" assumes that the pressure at an area only depends on the weight of the cylinder over that area. To prove that you need the hydrostatic equation that you derive. The proof assumes the proof. No proof at all.

@JamesCharbonneau 3 ай бұрын

You are correct, it is not a proof, it is a derivation. One thing that separates physics from math, and one thing that many people who want an axiomatic, proof-like structure struggle with in physics, is that physics always requires a jump in intuition to connect what we observe in the world to the math we use to describe it. You are correct that we made an assumption that the weight on the top of the cylinder is only from the fluid directly above it. This isn’t a ridiculous assumption. The weight that a bathroom scale measures is from the objects on it, and not beside it. However, fluids are different, and it’s a valid question. The thing is though, when we make this assumption we this equation that turns out correct. The “proof” comes when we verify this equation using experiments. But even this isn’t a “proof” you would get in math that this equation is exactly correct, but it is the best we can do in physics. The reality is that all of physics is constructed out of circular logic. You could derive a formula for the hydrostatic equation making a different starting assumption. For instance, you might think that the weight on the top of the cylinder is given by all the fluid in the container above the cylinder, and derive your equation. You then need to test it. This equation fall aparts very quickly when you run an experiment. If the pressure were equal to the weight of all the water in the container above you, then when you submerse yourself in the ocean you would get crushed by all the water above you. You have probably done this one yourself-when you submerse yourself in the ocean you do not get crushed. So because of that we can rule out this assumption. There are many other assumptions you could make and check, but the one that works and reproduces the measurements we see in the real world is the one we start this derivation with. You are right it is not a proof. But you should be aware that all of physics is similarly circular. There is not a single equation that you can derive from first principles. They all have an assumption or intuitive leap that has survived experimental tests.

@vladimircastanon9682 3 ай бұрын

Woah what a well explained video, you truly simplified error propagation so well, hats off to you sir well done, thank you!

@JamesCharbonneau 3 ай бұрын

@@vladimircastanon9682 Thanks! It’s one of my favourite things to teach because it’s so useful.

@jyotsnagoswami2000 4 ай бұрын

why aren't we considering weight to be one of the downward forces? after all, doesn't the upward pressure also have to cancel out the weight of the water cylinder?

@JamesCharbonneau 4 ай бұрын

@@jyotsnagoswami2000 This is a derivation of the buoyant force that is pushing the object upward. If you wanted to find the net force you would consider the downward force of the weight as well: F_net = -mg + F_ buoyancy.

@jyotsnagoswami2000 4 ай бұрын

@@JamesCharbonneau thank you for the answer, but wouldn't the buoyant force have to push up against the weight as well?

@JamesCharbonneau 4 ай бұрын

@@jyotsnagoswami2000 Yes, when finding the net force on the object you need to include the weight of the object. The buoyant force is the upward force on an object due to a displaced fluid. The weight is a different force caused by gravity acting on the object. Both contribute to the next for on an object and work opposite to each other. Perhaps it would help to see it used in an example problem: kzbin.info/www/bejne/e5Pbaoqnbc9-qLssi=sTr_idlbd7vCQrLf.

@coftas 4 ай бұрын

very useful, but some units ...

@lofi.30mviews 4 ай бұрын

Thankyou sir...huge respect from India....I was in trouble....great video 😊

@DrisrarAhmed-bd7bs 5 ай бұрын

WOW! JUST WOW❤❤

@TheDweller- 5 ай бұрын

Veryslowed down

@reinhardt0731 6 ай бұрын

thanks for making this simple I finally understand

@JamesCharbonneau 6 ай бұрын

@@reinhardt0731 Glad you found it helpful!

@darkerufo 6 ай бұрын

I'm here pretending Paul Rudd is teaching me about waves

@JamesCharbonneau 6 ай бұрын

@@darkerufo haha, I’ll take the compliment.

@vanizaidrees_khan9448 8 ай бұрын

Thank you sir

@krishnannarayanan8819 8 ай бұрын

Telling that it is a fractional part really helped! Thanks!

@JamesCharbonneau 8 ай бұрын

Thanks. Describing it this way was when I felt like my students were starting to really get it. Glad it helped.

@vi-xs2xf 9 ай бұрын

Excellent video James! I will name n=mym first born child james. thnak oyu james

@DominoFiles 11 ай бұрын

Thank you very much for this video. Only in my adulthood do I finally understand how this works (and not just by memorizing some formula). I intuitively thought that it must be because of the difference in pressure and had to look it up. Your video is on a perfect level of abstraction needed to fully understand this phenomenon.

@JamesCharbonneau 11 ай бұрын

Thanks for the kids words! I’m glad it was useful for you.

@STEMFA Жыл бұрын

Am not that much convinced 😢 2:26

@JamesCharbonneau Жыл бұрын

Could you clarify? Is it the substitution?

@bizon1271 Жыл бұрын

Indeed a wonderful explanation. From Italy.

@coenmolyneaux9672 Жыл бұрын

wow great video thank you so much. This helped me so much

@JamesCharbonneau Жыл бұрын

Glad you liked it!

@ericliu3328 Жыл бұрын

thankyou

@25kennethwu19 Жыл бұрын

thank you!!!!

@mercedesei Жыл бұрын

how did you know the cube is 1.1 m in the inside?

@JamesCharbonneau Жыл бұрын

The outside dimension of the box is 1.2m. The walls are 5cm = 0.05m thick. The outer dimension accounts for two walls, one on each side. So, the inner dimension is the outer dimension minus twice the thickness of the wall: 1.2m-2*0.05m = 1.1m.

@zeeshan123633 Жыл бұрын

nice

@carmelpule8493 Жыл бұрын

The manner in which I like to see a travelling wave (Signal) is as follows. Assume we have a picture of the Mona Liza which is 2 meters wide and and we can view it over 2 meters as it is when it is stationary. If we want to send it to another destination we can put it on a long moving platform, as with a driver driving a long train moving at velocity (c1) in the direction of "propagation".After time (t) the distance covered will be (c1 t) and while on this fast moving platform no one could recognise the picture. What we can do to be able to recognise the picture is to have a man running back on the moving platform with velocity (c2) holding the picture. The distance he covers with respect to the driver of the platform will be (c2.t) and if (c2 t) equals (c1 t) then we can easily view the Mona Liza over its width, as the picture will be now stationary. Rather than dealing with ever growing distances (c1t) and ( c2t) and the 2 meter width of the picture we could go periodic, hence the ( c1 t) can be an angle (2pi/wavelength1)(c1t) and ( c2 t) can be an angle (2pi/wavelength2)(c2t) and if the frequency we consider is f then (2pi/wavelength1)(c1t) = 2 pi f t =wt while (2pi/wavelength2)(c2t) =-kz Hence the angular displacement of the moving platform and the man running back will be ((wt -- kz) plus the angle A due to the width of the picture) hence this can now be written in rotating vector function of form as M e^j((wt -- kz) +A) At time t-0 and z=0 then we have the signal equal to M e^j( A) and it is easy to view the signal over this small angle A representing the width of the Portrait of the Mona Liza. At time =t and z= z such that wt--kz always equals 0 then the remaining function will be M e^jA) which makes viewing the portrait easier, through sweeping a small angle A, representing the width of the portrait (signal) on the travelling wave where, M e^j((wt -- kz) +A) may be plotted with respect to t or z. Most people call this a travelling wave but taking with respect to a reference which is the difference between wt and kz it becomes a wave with no relative motion to the reference taken! Congratulations on your videos. Thank you for referencing this video

@carmelpule8493 Жыл бұрын

Could one explain it as follows? If one has a signal generator which sets the signal A e^jwt which has the angular frequency w and so the angular displacement due to the signal generator is wt. Then if this signal is applied to a transmission medium which has an impedance which decides the natural velocity of the wave along the transmission line in the direction z then the signal applied, Ae^jwt, will be delayed due to the limited velocity c of the transmission line, and so the distance along the line is z= ct. This distance z or ct along the line will mean that along the line there is an angular displacement of ( 2pi/ wavelength) ct where ( 2pi/ wavelength) =k Hence what goes on along the transmission line may be described by what happens in the signal generator and the delay on the line so A (e^jwt)(e^-jkz) and z can be expressed as ct. The interesting issue about this is that at t=z= 0 the wave is a constant while if the time angular rotation wt is made to be always equal to the angular rotation on the line -kz then we would be moving along with the wave as ( wt-kz )= 0 and the wave will have the same amplitude as what it started with at time and z = 0. This is relativity at its best!

@JamesCharbonneau Жыл бұрын

If I follow you, yes. The wave velocity is c = wavelength/period, so your formulas for the angular displacement (2pi/wavelength) ct becomes 2pi/period t, which gives the angular displacement after some time. You should get the same angular displacement for a specific z and t no matter which way you are looking at it because you a describing the same physical object, a wave. I think this is what you are getting at. Perhaps looking at this video would be helpful: kzbin.info/www/bejne/amm5cqerrqiehJo. It combines the descriptions of angular frequency, wavenumber, and velocity in a concrete way which is I think what you are looking for.

@carmelpule8493 Жыл бұрын

@@JamesCharbonneau You do follow me perfectly, Thank you for replying,

@Royalindianrecipes Жыл бұрын

Basically net upward force is more5 不 B o (Net The bressure exerted by the liquid on the phase AD and BC is equal Pressure exerted by the liquid on the top is downwards and on the bottom is upwards. Totol downward Force F-Pressure X Area F= Pa [F₁ = (h,dgia] (dis density) (P= h.dg also) 0 Upward force exerted by liquid Ep Pressure x Area Fp= (h₂dg) a,

@deepajkuri4636 2 жыл бұрын

sir, can you make us understand about e=mc^2

@Timo-lu3eu 2 жыл бұрын

Hi, my question is if this also works for light or just for sound?

@JamesCharbonneau 2 жыл бұрын

Good question. The idea is similar for light, and the derivation is the same up to a point. A key difference is that when objects are travelling close to the speed of light we need to take into account the effect of time dilation of the measurement of the frequency. When this is done, the formula is a little different and you get the relativistic Doppler effect. Also, the formula becomes the same for a moving source and moving observer, which is consistent with relativity. Hyperphysics hyperphysics.phy-astr.gsu.edu/hbase/Relativ/reldop2.html has a pretty good comparison of the differences in the two formulas.

@Hyyyyy99 2 жыл бұрын

Thanks a lot sir 👍

@rajparekh7581 2 жыл бұрын

Thank you so much! This is all I needed!

@Izaac_Artist 2 жыл бұрын

Oh so that'd what they do I've never realized it before wonder if raptors did that?

@toomobs 2 жыл бұрын

Sorry, but sir you only show that the BLs are equal. However, there's intuitive but no evidence that if the distance from the coil approaches infinity the BL of that side is zero, so we cannot make the argument that BLr=BLl=0. It draws me to the analogy that the E field at a point caused by an infinite big plate is not related to the distance between the point and the plate:imilarly, the object is big. Thank you, sir.

@JamesCharbonneau 2 жыл бұрын

Good question. There is another commenter here that asked almost the exact same question. Thought my response to that one is useful to read, I want to address your analogy with electrostatics. It actually leads to a cleaner arguement. The solenoid is closer in analogy to a capacitor, which we model by two oppositely charged infinite planes. We know that when we put one plane next to the other, the negative field from one cancels the positive field from the other when they are outside the capacitor. We can build the same thing with two sheets of current, one going into the page and one going out of the page. This is easy to imagine with my cross section drawing inn the video. Each infinite sheet of current has a constant magnetic field from it (B= I\mu_0/2L and we let I/L be a current density), just like an infinitely charged plane. However, when we put the two sheets next to each other, the field outside cancels, just like in the electrostatic case, and we get B = I\mu_0/L, just like we would expect. Now, a solenoid is just what happens when the two planes of current wrap into each other. Most importantly though, the reason we set it to zero outside is because we can assure the field just outside the solenoid. Just, like for a capacitor. It’s important to remember that in physics we often need a physical measurement to get the answer.

@colorx6030 2 жыл бұрын

THANK YOU

@jonathanwilson7957 2 жыл бұрын

What the speed of this video? It has to be sped up

@JamesCharbonneau 2 жыл бұрын

The time scale is about 20 years. The year count is in the bottom right corner of the video.

@KyriakosXns 2 жыл бұрын

You didn’t help

@JamesCharbonneau 2 жыл бұрын

Sorry to hear that. This solution is made for a course taught at UBC. Without the course, some things might be missing. What didn’t you understand? Perhaps I could fill some things in.

@whattheheck1001 Жыл бұрын

I think the units for the heights should be in meter

@csepelcharlie8389 2 жыл бұрын

Wow, that's beautiful. Thanks for sharing!

@JamesCharbonneau 2 жыл бұрын

Thanks! I’m glad you liked it.

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