Physics 44 Magnetic Field Generated (27 of 28) Ampere's Law: Solenoid

[@kabandajamir9844]

The world's best teacher thanks sir

[@MichelvanBiezen]

Thank you. Glad you like our videos.

[@hecz250]

Thank you. You've quickly become my go-to life saver for this class.

[@petroslazanis8466]

Michael Van Biezen taught me what a solenoid was in 15 seconds, whereas my professor took a 20 minute video to convince me to drop out of university,

[@Nioxsae]

Thank you, I'm doing a physics investigation for year 12, and when I tried to derive this equation I was getting B=(μoNI)/L in the horizontal direction to the right, and everywhere I looked it had B=μoNI and I was wondering why, and this gave me the answer!

[@MDGupta-pr7nd]

many many thanks to you sir when you explain this stuff I understood it completely . BIG thanks

[@johannwegmann4365]

Professor van Biezen, I enjoy your classes and qualities of real cathedratic.If you please adress me tosome class of yours, 1.-with an ample field flux lines or mag density flux inside and outside space simulation. 2.-If a vector field equation exists, I saw, we need an Equation 3.-Solenoids linear electromagnets engines demands the force on the plunger ferromag.material from N to S pole inside the coil, 4.-If we draw a perpendicular against axis of symetry (center of coil=along l) and draw the flux lines from N the cenered ones will not close as a loop to S, will be asymptotic to the perpendicular to infinity.Why this is important to day, because electromagnetic engines are demonstrating to more convenient simple and reliable and cheap than classic electricmotors. 5.-We engineers are all enthusiasted because you need a few elements and thats it, funny. 6.-Many exposers of their achievements say : the motion of plunger is unstable,the force and speed along x axis of symetry is unknown, they asume a drop in F and v from x=0 and x=l, a great concern is what happen in l/2, a great inflection,so B=B(x) is necesary 7.-I heared v=f(volts ) 8.-Last question Professor,if plunger is a permenent magnet N S fixed,is it better than a soft iron. Best Regards,thanks fr your classes. Johann Wegmann

[@mivapusa]

Bless you, your teachings and your butterfly :D ...seriously, your explanations are making this much easier to comprehend.

[@Nafana]

Very good explanation!

[@Abu-cb6bj]

best explanation. thanks sir

[@AhlaAklah]

Could you guide me how to build up lap solenoid 2 tesla for doing an experiment I need it to rolling up a tube with 3 cm diameter and 15 cm length ?

[@Megatron118x]

Great video as always! Question though: does the direction of your integration path for dl matter? You have it clockwise, but what if we wanted dl to go counterclockwise? Is the choice arbitrary? I tried it myself and simply got a negative sign, which I suppose makes sense depending on how you define your coordinates. Just thought I’d ask for clarification

[@MichelvanBiezen]

The direction is NOT arbitrary and as you indicated you will get a negative answer if you integrate in the opposite direction.

[@Megatron118x]

Michel van Biezen So do you have to have an intuition ahead of time to choose the integration path that yields a positive magnetic field? Or I guess more generally, HOW do you decide which direction to integrate? After this clarification, I understand everything else. Thanks again!

[@Megatron118x]

PikachuSkywars Better late than never! Haven’t done electro in these 2 years so I’m sure my skills are rusty haha, but it’s stored in deep memory I hope! And yes, that makes sense, thanks!

[@johnbennett4002]

Hi Professor, What is bothering me is the enclosed current. If 2 amps go into the solenoid, 2 amps should come out to obey charge conservation, or KCL. So why does the enclosed current get multiplied by N? Why is the enclosed current greater than what is provided by the source? The enclosed current should always be same. Thanks, -John

[@MichelvanBiezen]

Note that we are calculating the strength of the magnetic field, which DOES depend on the number of turns (loops) per unit length of the solenoid. The current is the same throughout the entire wire and does not depend on the number of loops. This video shows why the strength of the magnetic field depends on the number of loops.

[@tushardwi2231]

@@MichelvanBiezen Understood thanks a lot!

[@donaldlin7308]

Michael, could you explain what B field looks like above/under the solenoid? If it's not 0, how would you calculate it? Thank you!

[@MichelvanBiezen]

Those would be very difficult calculations. We tend to approximate such things which is typically good enough for most applications. This is something that is better shown on the white board than explained like this. When I get going on the advanced E&M videos, we'll see more complicated examples like that.

[@donaldlin7308]

Thank you very much Michael. Your videos have been very helpful, thank you!

[@joshuajanssen9655]

Thank you, this was very helpful!

[@mikehawwke]

can you please show how magnetic field is constant inside solenoid

[@khushantrana4495]

Sir plz upload video on magnetic field of finite solenoid

[@jackiechiu20]

Hello sir Thanks a lot for your explaination But from the lesson, you have only used the upper part of the coil. Then how about the lower part? should Bl = 2uI

[@MichelvanBiezen]

No, the result is correct. Note what would happen if you lower the bottom dashed line below the solenoid. Then I enclosed would be zero.

[@jackiechiu20]

Michel van Biezen Thanks a lot I understand by Ampere Law Bl=ui enclosed in a straight current line. But now this is a close circular current loop. It is similar to have infinite straight line current. Why the magnetic field inside the loop is not that infinite straight line current sum.

[@MichelvanBiezen]

You can't say that a current loop is "similar" to a straight line current. The magnetic field acts very differently.

[@jackiechiu20]

Michel van Biezen Thanks but i am still confused.

[@jackiechiu20]

Michel van Biezen Sir, from your previous video about Boit-savart's Law, the result of the magnetic field at the centre of the current loop is ui/2a. Can it be used to find out the magnetic field of the soleniod.

[@zakhamdan5575]

Hi! Thank you so much for the video. I have a question. Can you choose what kind of Amperian path you integrate around? My suspicion is no because of the symmetries, but since I'm not entirely certain of how symmetry influences the Amperian path, I'd like to make sure.

[@near2196]

You can choose whatever closed path you want but always stick with the best path according to the syetry of thw problem to massively simplify the theorem. The theorem was literally made for choosing a path with a constant magnetic field and so that you only need to integrate a dl. If youc hoose another geometry here, you might need to integrate and calculate the dot product , which can result in nightmares at night :)

[@YellowHalo]

hi Sir, could you please explain how this formula came about, N(number of turns)*D(Diameter)=L(Length of solenoid), i can't figure it out, i saw it on the internet.

[@MichelvanBiezen]

Take a look at this video: Physics - E&M: Magn Field Generated by Moving Charge & Currents (27 of 28) Ampere's Law: Solenoid kzbin.info/www/bejne/rpXWiYOVoZiklZI It explains where that formula comes from.

[@taladiv3415]

Dear van Beizen should receive my lecturer's salary because I learnt from him much more than I could from my lecturer!

[@mikehawwke]

WILL MAGNETIC FIELD INSIDE THE SOLENOID NOT BE CONSTANT IF CURRENT DISTRIBUTION OF WIRES WRAPPED ARE NOT UNIFORM. Sir can you please clear this doubt of mine, I will be very Grateful

[@MichelvanBiezen]

The magnetic field is much more complicated than the way we model it here. Towards the ends of the solenoid, the field begins to change and is thus not uniform all the way through.

[@ankitrajput3204]

Sir what's the reason why B reduces to half at the edges?? Why it is max at the centre??.

[@MichelvanBiezen]

The magnetic field strength is the result of the sum of all the contributions of the currents nearby. At the edge, there are no contributions from the region where there are no loops.

[@bn7809]

Can we find the magnetic field inside one circular current carrying wire by using ampere's law? If yes how do we do it?

[@MichelvanBiezen]

We typically don't do that. That would be very difficult in a real situation since the current doesn't "flow" evenly through a conductor.

[@bn7809]

Oh okay, thank you very much.

[@Rishabh-rc4zs]

Great video

[@MichelvanBiezen]

Thank you. Glad you liked it.

[@rjaph842]

Does pulling out the magnetic field in line with the fact that it is assumed to be constant?

[@MichelvanBiezen]

Assuming the B is constant gives us a good approximation for most situations.

[@dylaninho2500]

Thank you, what if there is a ferrous core in the solenoid?

[@MichelvanBiezen]

That will enhance the magnetic field.

[@dylaninho2500]

@@MichelvanBiezen Is there a way of representing it mathematically?

[@bugrahanatar2205]

sir, Why the B has a maximum value on the half of the wire?

[@klevisimeri607]

Thank you!

[@MichelvanBiezen]

You're welcome! Glad you found our videos. 🙂

[@abhinav4095]

Can u explain how you took the direction of current in your amperian loop?

[@MichelvanBiezen]

The dots mean the current is coming towards you. The crosses mean the current is moving away from you. (looking at the back of the arrow)

[@drhf1214]

thank you so much~

[@QutipahAlajarma]

والله انك روووووعهamazing 👍🏻👍🏻✨✨✨✨✨🇯🇴🇯🇴🇯🇴

[@moratasa9741]

رؤؤؤؤوعة

[@vedangpathak]

Why magnatic field outside the solenoid is zero ???

[@MichelvanBiezen]

The magnetic field outside the solenoid is NOT zero. But the integral of B x dl is zero, because the direction of the magnetic field is parallel to the direction of travel. (sin 0 = 0)

[@arcstur]

Thank you

[@michaellewis7861]

Do you have no videos on Bio-Savart’s Law?

[@MichelvanBiezen]

You will find those in this playlist: PHYSICS 44 MAGNETIC FIELD SOURCES

[@speciallitylyngdoh1637]

why do we have to integrate all the part

[@MichelvanBiezen]

You want to integrate over the length of the tube that is covered by the wire.

[@lisajose9219]

Good

[@kazet1177]

great video

[@MichelvanBiezen]

Thanks! 🙂