What is Flux? + an Introduction to Gauss Law (Electromagnetism - Physics)

[@hendismutandwa1409]

If my comment makes a difference then allow me to let you know that you sir are a man of your craft....it's easily relatable and becomes more of common sense when you use such analogies to explain these complex physics concepts. You just gained a new student and a subscriber! Thank you for the lesson; awesome, fantastic!

[@PhysicsMadeEasy]

Thank you Hendis for these very encouraging words!

[@dominicestebanrice7460]

At 08'20" "Magnetic flux density and magnetic field strength mean the same thing"......THANK YOU for stating this explicitly and clearing away the ambiguity that exists around these terms!

[@PhysicsMadeEasy]

Hi, yes thank you for noticing: as a teacher, I observed that the terminology could be a source of confusion for my student , so I systematically clarify this. Note that you could also call an electric field strength, an electric flux density. It also works!

[@peeranutpompim3276]

RIGHT???? I’ve been going crazy wrapped my head around all the definitions for Flux

[@spencerwenzel7381]

First time I feel I deeply understood the concept of flux. Thank-you for the amazing video 👍

[@PhysicsMadeEasy]

Hi Spencer. Some school teachers kind of bypass some basic notions, which leaves students quite confused when arrives the time to use them. Hence, the Physics Made Easy channel! Thank you so much for your feedback!

[@mdnurainansari3414]

These days I'm in love with physics and Your videos motivates me, How amazingly you teach physics

[@PhysicsMadeEasy]

I am so glad my work inspires some love for Physics in students. Thank you for letting me know it has this effect on you!

[@CBMM_]

Thanks!

[@PhysicsMadeEasy]

Wow, thank you so much Greenzilla for your gift! It truly encourages me!

[@ambred2184]

oooh wow thanks !!! very useful as a bachelor student, i often watch your video and they reaaaally help me but this one deserves a raise!!!

[@PhysicsMadeEasy]

Hi Ambred, thank you so much for your kind feed back :-). I am glad my work has truly helped!

[@Hazaardd]

One of the best physicist in the world 🙂

[@PhysicsMadeEasy]

*** blushing *** :-)

[@hiworld7306]

Thank you so much sir for coming back. Hope you will post more videos on electrostatics. You made my day.

[@PhysicsMadeEasy]

My turn to thank you for your kind encouragements. There is a new video related to electromagnetism in the pipeline. It will be released next Tuesday (Sept 12): The title is "What is a Magnetic Field?". I hope you'll enjoy it!

[@hiworld7306]

@@PhysicsMadeEasy Thank you sir you made my life so much easier especially that electric potential.

[@acelyasevil5398]

You are a hero sir!!!

[@PhysicsMadeEasy]

Well that's a new one haha! Thank you for seeing my work as Heroic ❤

[@TheElectromagno]

Very good explanation. Creative and at the same time very profound .

[@PhysicsMadeEasy]

Thank you for your kind words! Cool nickname by the way :-)!

[@yogahariharan4532]

Your videos are awesome and glad that you are back. 🔥 Waiting for more topics about electromagnetism from you

[@PhysicsMadeEasy]

Hi yogahariharan, Thank you :-), yes, there is a new one cooking...

[@manav5350]

Glad to see you back

[@PhysicsMadeEasy]

Thank you Manav. Glad to be back! To celebrate this, a new video is on its way. I hope you'll enjoy it!

[@jonathanlister5644]

This is an excellent introduction to Gauss' Law thanks!

[@PhysicsMadeEasy]

Hi Jonathan, I am glad you enjoyed it. Thank you for the praise :-)

[@shivamtiwaryslp8422]

Sir your teaching style is very nice 🙂 Love from India ❤

[@PhysicsMadeEasy]

Thank you for your kind feedback Shivam

[@PS-pb3qy]

Sir u are back plz be regular U are big help in my high school thank you

[@PhysicsMadeEasy]

Hi... I am glad my videos help you with your studies! Sure, I would like to be more regular... but... making these videos takes huge amount of time (remember I do everything, even the music!), and Physics Made Easy is more of an extension of my teaching activities, a kind of big hobby... A new video is cooking though, and should be out soon :-)

[@leoclarkin5944]

Well-presented, clear & concise, very much thx

[@PhysicsMadeEasy]

Hello Leo, thank you for your kind words :-)

[@ranusingh9799]

sir you are back 🎉

[@PhysicsMadeEasy]

🎉 :-)

[@breathdryang]

Thank you so much Teacher.

[@cristianramos5546]

Incredible video! Thank you sir.

[@PhysicsMadeEasy]

You are welcome Cristian, I am glad you enjoyed my work :-)

[@e-nq5ro]

You’re amazing. Thank you

[@PhysicsMadeEasy]

❤️❤️❤️

[@jakirshah1683]

It's really very comprehensive🎉

[@PhysicsMadeEasy]

Thank you for the compliment Jakir

[@everythingeverything7672]

You are #1, I want good explanation from you..☺ about 1#Information and #Energy ; 2 #Frequency and #signal 3 How can #charges carry #information

[@PhysicsMadeEasy]

This is basically signal processing. My videos deal more with fundamental physics... Maybe one day, I'll explore that kind of stuff . To try and discuss this topic in a few sentences. Basically, if you want to transfer information via electrical means, it's by imposing a binary variation in time of the electric fields within the signal emitter (which for example leads to a voltage of 5V (a 1) and 0V (a 0). Then the propagation of that changing electric field transports the info. Subject 1: You need a source of energy to generate an electric field that you can turn on and off for 0 and 1. Subject 2: The frequency is that of a clock. the rate at which you turn on/off the field should be synchronized to such clock so that the emitter and receiver can communicate reliably. Subject 3: It is not a charge that transport information. it is the propagation of the electric field state (at the speed of light of the medium ). You can image this like a square pulse that would propagate on a rope...

[@The_Green_Man_OAP]

7:41 I think it's a misnomer to label variables that are not functions of time with a _d_ in front which means _change in_ , which happens _over time_ ( in _Physics_ ). I think we should distinguish _change_ (difference resulting from an _action_ over _time interval_ ) from infinitesimally small pieces of things like areas, volumes..etc (difference over _space_ , i.e. _position_ at _fixed_ time ). So, for a surface that _changes_ , _dA_ can describe this _shaping_ process _within_ a time interval _dt=t' -t_ ; but if the surface considered is at an _instance_ of time, (a _time ordinate: t_ ), and what is required is a subdivision of a surface, use a symbol denoting _spatial difference_ like _δΑ_ , which is independent of any _time interval_ , but can be assigned a _t_ value for that _instant._ *Summary:* For a _surface difference_ with: 1. time _change_ or _action_ : (i) Temporal infintesimals "d" => Calculus rules: Use (dA ,dt), with dt=t' -t and dA=A' -A; Total time period for the entire motion=T. Subdivide this: let dt=T/n, n= # d values. # d values depends on how many impulse actions have happened to the system. (ii) Finite interval "∆" => result of integral or "difference equations"=> No direct calculus: Use (∆A,∆t), with ∆t=t'-t and ∆A=A'-A. 2. time _instance_ : Spatial infinitesimals "δ" => Calculus rules: Use (δA, t), with δA=Total area/# δ values i.e. Subdivide total area "A" into bits: δA=A/N. In general: # impulse actions ≠ # spatial elements i.e. n≠N, dA≠δA.

[@PhysicsMadeEasy]

Hi again, thank you for your interesting comments by the way. We have a completely different understanding of the notation, I think it is a difference between maths and physics... In maths, everything is clearly codified...In Physics, context provides the understanding of the notation. (it's like the difference between Japanese(=physics) where context gives the meaning to the words and German (=maths) where the words provide the context). dx noted alone, is not dependent on time by essence, it just means infinitely small interval of x. If there is a relation of x with time, then it will shows up as dx(t), or written somewhere else in the text or in a neighboring equation (then dx is assumed to be dx(t) δx means small quantity or even fractional quantity, used, for example, when representing the charge distribution in a hydroxyl ion (-δq on oxygen and +δq on hydrogen). It can also have the same meaning than ∆ but for small quantities, in nuclear physics for example: the mass defect is sometimes written δm like a reminder that we are talking of a tiny fraction of the reactant's mass. Sorry this is a physics channel ;-) Thank you very much for your comment, it made me think. ❤️

[@breadblank9509]

yoo the background Music is fire 🔥 🔥

[@PhysicsMadeEasy]

Thanks! I actually compose and produce the music in the videos. The music on this one is the first track of the "Physics Made Easy" album. Check it out here: edouardreny.bandcamp.com/album/physics-made-easy-the-soundtracks

[@Kiros-r1q]

I'm from Ethiopia thank you teacher

[@PhysicsMadeEasy]

You are welcome.

[@jonathanlister5644]

lovely and I think your cats must understand too!

[@PhysicsMadeEasy]

Finally! Someone notices the drama that was going on in the background of the video section with the board, haha! Yes, my cats adore Gauss Law ;-)!

[@jonathanlister5644]

Two highly charged cats displaying their fluxes, these crazy cosmologists talked about spherical cats being strokable everywhere.

[@wus9472]

Thank you sir for excellent presentation of a difficult concept. I have a question , so you mean to say if only the magnitude of the E field changes without changes in the field lines thorough a specified fixed area then the flux remains unchanged?

[@PhysicsMadeEasy]

Hi Wus, E changes if the density of field lines changes. The Flux is measured by the number of field lines. So if the number of field lines remain the same, so will the flux. Your sentence is incorrect because you say the "specific fixed" area, for the density of lines to change with the number of lines remaining the same, the area (or its orientation) needs to change. Does this clarify things?

[@kaixin3930]

thank you sir , You saved me ))

[@PhysicsMadeEasy]

I am a savior now ? I am just a teacher haha! I am glad my video helped you. Be well.

[@ashishkalra9661]

Thank you

[@sshreddderr9409]

electric/ magnetic and gravitational field are just terms for different configurations of the same superfluid that fills the space or is today just named vacuum. The reason why fluid analogies are always used for electromagnetism is because it is a flowing fluid in a pressure field. the term "field" itself actually is just a pressure differential and the resulting force, and only makes sense in the context of fluid. everything that can be described with fields by definition must be a fluid in motion.

[@PhysicsMadeEasy]

In classical physics, fields are a model that is introduced to characterize action at a distance. Like the concept of force simplifies the understanding of the interaction between two bodies... These are just conceptual tools. However, in quantum mechanics, the consensus is evolving towards the idea that fields are actually the real deal. And besides, you have scalar fields too... some are not necessarily a direct tendency to (fluid-like) motion...

[@sshreddderr9409]

@@PhysicsMadeEasya field is just a mathematical model of a primitive fluid without calling it fluid. force implies pressure, and pressure implies pushing, which is mechanical in nature, meaning there needs to be a medium to transmit the pushing. there needs to be something that is pushed against. talking about force and pressure implies a mechanical medium. the essence of what it means to be a fluid is what a field is, its just that the medium requirement is intentionally omitted form the definition of fields to make it appear distinct. the same characteristics that make water wave exist in everything that waves. waves wave because there is a medium with internal pressure that seeks pressure equilibrium, and a disturbance in the medium presses against the fluid and disturbs the equilibrium, and because there is internal pressure, a wave motion is the result. same thing with electromagnetism and gravity, and any force.

[@sureshakella4263]

Thanks

[@danblankenship5744]

What is the difference between electric flux and magnetic flux? I have always thought Gauss referred to the magnetic flux. We demagnetize objects with a degaussing coil.

[@PhysicsMadeEasy]

The "Gauss" is actually a unit of magnetic flux density (1 Tesla = 10000 Gauss). That's why the degaussing coil is called that way. It could have been called a Deteslaing coil, haha! The first Maxwell equation is called Gauss Law and is related to electric fields.

[@profelu1919]

That is, indeed, cool.

[@AbbasAzani]

In 7:40 why can we consider the electric field strength constant?

[@PhysicsMadeEasy]

Hi Abbas, because by definition, a differential area is infinitely small... Analogy: the surface of the Earth has a curvature, right? because it is a sphere. But now let's consider a very small fraction of the surface of that sphere like that seen by a human: the surface appears flat (with a curvature of zero)... Gravitational field lines generated by a spherical body are always perpendicular to its surface, so for a human being on the surface of the Earth, the gravitational field is constant in magnitude and direction (g = 9.81 N/Kg downwards)...

[@AbbasAzani]

So..X is a function that describes the field strength at a point (x,y,z), delta area can be thought of as a point. So the value of the field strength is constant for that delta area. Is that it? Thank you for replying, I really appreciate it. Love from a highschool student in Malaysia❤

[@PhysicsMadeEasy]

@@AbbasAzani Yes Abbas. if it helps you can think of it as being as small as a point that's why the field remains constant. But be careful, make sure you keep this idea as a mental tool that you know is fundamentally wrong: dA, is an area of infinitely small size, and despite being that it still has two dimension. A point has no dimensions, so no size....

[@The_Green_Man_OAP]

14:48 Used _dA_ earlier on (should be δA according to me), now uses _ds_ ... _Why?_ I realize that "s" means _surface_ , but "A" means _area_ and you just went and changed them for no reason... 😕 Also, "s" is used in SUVAT equations (s= _displacement_ ) or it can denote an _arc length_ along a curve, so it might be a bit dangerous to say its a surface area element.

[@PhysicsMadeEasy]

Yes, I ran into trouble there, haha... but not the way you think... I use A for an open Area, and S for a closed area (S stands for surface of a volume). But when I shot the video, I said A when presenting the flux through a closed surface... so modified the illustrations to put A instead of S... In the section with the board, I used the correct designation. I teach various programs (IB, AL, AP, French Bac, etc). they all use different symbols for same concepts, so when on KZbin, where students can come from a bit everywhere, I try to use the most 'intuitive one', hence A and S. When using the suvat method, s is used for the displacement, please note that many programs present motion equations differently, with x and x0 instead of s, v0 instead of u etc... Concerning the notation for a differential, I detail this in response to your other comment.

[@physicsbyDKBhuriya]

Very NYC viddo

[@Attalla-t9b]

7:51 i wonder why we integrate it from A into ... (is the nothingness supposed to be a variable?)

[@PhysicsMadeEasy]

At 7:51, we are integrating the flux density X over a surface A... If the surface around the source of flux is a sphere, the flux density will be the same on all its surface, so we would just need to multiply. But if the surface is not symmetric, than the flux density will depend on which part of surface you are considering, in that case you need to integrate the flux density X across the surface A. Does this help?

[@ihabsglei]

Don't these considerations only apply if some kind of continuity equation is assumed? This is obvious for non-compressible liquids in pipes, but does this also apply to static electric fields? For example, cases are conceivable in which the field line density remains constant in the underlying vector field, but the field strength increases. The flux would have increased, but the number of field lines counted through the surface would remain the same. 🤔

[@PhysicsMadeEasy]

Absolutely. Such equation can be derived from Maxwell's equation. "For example, cases are conceivable in which the field line density remains constant in the underlying vector field, but the field strength increases" What case? If the field line density remains constant, so does the field strength. The flux cannot increase without increasing the number of field lines...

[@robertbatista50]

I know this is unrelated to the current topic, but why is it that every textbook takes the reciprocal of a single charge and then uses this number as the total number of electrons assigned as 1 Coulomb? Can you please do a video on this, no one has ever addressed this on KZbin.

[@PhysicsMadeEasy]

Hello Robert It is a simple cross product... An electron carries a negative charge of -1.6x10^-19 Coulombs. How many electrons are needed to carry -1 Coulombs? Well, you just divide -1 Coulombs by the charge of an electron, and you get the number of electrons that are needed to carry - one Coulomb... Number of electrons = -1 Coulomb / Number of Coulombs carried by one electrons = -1 / -1.6*10^-19 = 1 /1.6*10^-19 I hope this clarifies it!

[@robertbatista50]

@@PhysicsMadeEasy, thank you. You are the best. Do you have a physics course specifically tailored to Electronics? I would like to take one.

[@PhysicsMadeEasy]

Hi Robert, I only have one course on electricity, but it is really basic (charge, electric force and electric fields, but nothing about circuits and electronics. I wanted to, but no time...)

[@physicsbyDKBhuriya]

Plz tell me which software u use to make video, beacuse I also want to make these type video , I m physics students so I humble request to u that plz provide my software or aap that u use ❤

[@PhysicsMadeEasy]

I use an old version of Camtasia I bought in 2016. And for the animations, basic powerpoint. No need for fancy things (for now)! Good luck with your channel!

[@physicsbyDKBhuriya]

@@PhysicsMadeEasy thanks 6 ur valuable suggestions. Ur explanation too good sir. I like ur video, because I m also physics teacher and I want to make video as yours ❤️❤️

[@VishalKing-t2n]

Very good sir I could better understand

[@PhysicsMadeEasy]

I am glad my video helped!

[@VishalKing-t2n]

Thanks sir I belong from pakistan i want to become a great person

[@RichardArthur-d9f]

Sir pls make a video on integration

[@PhysicsMadeEasy]

Hi Richard, thank you for the suggestion... I am not a math teacher... There are very good math channels out there, explore!

[@FD-rt3rv]

Yes we know that 🌈

[@PhysicsMadeEasy]

:-)

[@taseen7256]

Oh to be the the two cats in the backyard chilling instead of a physics 2 electrical engineering student about to fail the first midterm.

[@PhysicsMadeEasy]

how do you know when the cats are meowing to each other, that there are not discussing the latest developments in quantum mechanics ;-) Courage to you with you exams. Try to work on as many past papers as you can and make sure you truly understand the markschemes (study them). Working by experience is also another way to link the dots and gain an understanding.

[@breadblank9509]

Kats 🐱🐱🐱

[@PhysicsMadeEasy]

haha! That shows that you've been watching the video till the end (The proof of Coulomb's law starting with Gauss Law). My cats can be quite dynamic as you have seen! I hope you enjoyed the video. Be Well, E.