Dielectrics in Capacitors and Otherwise | Doc Physics

[@MoizAsimagar]

Teachers like you are the True Teacher who love Teaching truly.... Others are just doing it as job. Your students are indeed very Lucky.

[@DocSchuster]

Thank you! I also hate being told to know things without understanding them. I think that motivates me to teach the way I do.

[@tomasbeals4592]

such a good explanation thanks!

[@chrismccoy587]

12:28 lol you're the greatest physics tutor on the internet!!! I love your passion, and you make it very understandable -- and you're THOROUGH in your videos, you show a lot of material. Thanks a lot!

[@ownall201]

Some people are just born to be teachers, and you sir have found your calling! Thank you so much for posting these videos(:

[@izzystreaks1807]

Your students are so lucky to have you!

[@hasan28234]

this is the first time i understand the polerized conductor ! no one explain it they just say know it without understand it thank u so much you are the best physicist

[@svetimina6173]

I'm watching your videos in place of TV. Love 'em!!!

[@fernandochoe5226]

please, come to ucla and teach physics. You explain much better than my professor.

[@DocSchuster]

Fernando Choe Just send me the employment contract! Thanks!

[@Harsh-zj7lm]

LOL! made my day...

[@devinyoung5735]

i'm taking 5C right now and Doc Schuster is my go to dude

[@O2Obaid]

VERY HELPFUL STUFF. I have a midterm after tomorrow and am willing to ace that SUCKER!!! :)

[@simranjoharle4220]

I wish you were my physics teacher...... It was just the kind of explaination I wanted

[@DocSchuster]

Nice work on the exam! PatrickJMT or the pretty girl at The Integral CALC can help you with math (singular, of course, on this side). They both seem to do a great job. I have to focus on topics that are beneficial for my real job at this point, but I'd love to talk about those cool topics, too. Not likely by the time you'd need 'em, though.

[@DocSchuster]

Air-gap capacitors are indeed very low capacitance. They are commonly used for adjustable caps for tuning (in antique radios and even in modern research). They'd also be good for high voltages, of course.

[@sirhuman560]

Legendary! i enjoyed the lesson so much cuz of your explanation. Thank you.

[@duncandonuts_21]

What is the relationship between the dielectric constant and the polarized electric field inside the dielectric? Do they have a linear or direct relationship?

[@TheDavddd]

What you said about "electric fields costing energy" sounds pretty profound but a little bit magical IMHO. Do you know where I could see more information related to this? Thanks. You're videos are great help as always.

[@DocSchuster]

David Villarreal I appreciate your skepticism! Look up "energy stored in electric field" or in grav field or in mag field. Join the ranks of the amazed! Surprise your friends!

[@WhiteBeansYT]

Hey, is the answer to the question at the end 3,000? Since you said kappa for air is very close to 1, and we use V = E0d/V0 we can get 3000000*0.001/1 = 3000.

[@EternusVia]

If metal has "infinite polarizeability", why not use it as your dielectric? Could someone help explain?

[@DocSchuster]

That's how it caught me, too. You've got to watch who you hang with - you'll start to talk gangsta like them.

[@pelikhano]

"We should always go green." Dear Doc Schuster, do you have something to say? Hehehe

[@MysticMD]

What happens if we put a conductor between a capacitor, not touching the plates?

[@DocSchuster]

Fun question. You've essentially installed two capacitors in series. They each have higher capacitance than the original due to the smaller plate separations, but they're in series, so that decreases the equivalent capacitance by 1/2 (assuming you've centered your inserted conductor). If you can get the plate separation quite a bit smaller, this process will still be beneficial to you. ON THE OTHER HAND, you've decreased the size of the gap, so the sparking opportunity has greatly increased. So your max voltage goes way down.

[@LockeStarr]

Dude, you're going to get me through my degree. Props.

[@akshaykale8018]

Can we use insulator as dielectric?

[@vivianagarzon3060]

Clear explanation! Thank you.

[@bvolpato]

2:20 you drew Milhouse from The Simpsons almost perfectly when showing the electric field lines

[@cheeese8015]

Very good video, better than my professor's explaination

[@LockeStarr]

Nailed the exam. If only you covered Maths and electronic systems as well. I don't suppose you do solid state devices, or mechanics? ;)

[@bindiasuthar3009]

U r too good sir...Salute you😇😇😇😇👍👍👍👍

[@Alfster18]

Awesome video! I was looking on the web for some typical dielectric materials for capacitors and air seems to be used sometimes. Although air would have a high breakdown voltage as you mentioned at the end, wouldn't it be one of the worst for capacitance as it wouldn't reduce the electric field inside the capacitor at all so the kappa would be 1 if I understood it right, so why do they use air?

[@bsce100]

I wish you were my electronic materials professor!

[@DocSchuster]

Yay! Go get 'em, tiger. (That's something we all say in the US. All the time. Really.)

[@vbcambajogai]

But why Voltage across battery is same as that across capacitor?

[@paulzeng4142]

finally what I'm looking for

[@TT-qn8zi]

If k =∞ for a piece of metal, isn't C = ∞ according to C=k C_0? It makes sense when explaining E-field=0 inside a conductor by E=E_0/k. But metal should have a C＜C_0 which means k shouldn't be ∞ but less than 1. Could somebody help plz?

[@hamadaldhanhani6502]

did I ever tell you that I enjoy watching your videos..

[@AhmedCr]

your the best :D nice job :D

[@Teppei9asone]

How is the k, the dielectric constant, of metals be infinity, 1/infinity is noway = 0, infinitesimal yes, but 0? That's saying something = nothing. And if k equals to 0, would conductive dielectrics make infinite energy storage since they create get polarized and cancel out immediately upon being charged on both of the capacitor plates. or is that impossible because no electric potential can occur across the conductive dielectric?

[@DocSchuster]

If you slice a loaf a bread into a billion equal slices, you'll have really thin slices. If you slice into infinite equal slices, the slices MUST HAVE WIDTH ZERO. Otherwise, you would have needed to start with an infinite loaf of bread. In other news, you are correct. You need an insulating dielectric so the charge doesn't just GO. I think if you can figure out how to make a perfect dielectric, you'd get pretty rich. Maybe no Nobel Prize, though...but it's worth a weekend, anyway!

[@yichizhang795]

Excellent!

[@adamkozlevich7282]

It is just great!! all I can say) Thanks a bunch!!

[@darthglowball]

So if metal has a near infinite dielectric constant, why don't we use that as a dielectric? Of course I'd coat the metal dielectric with an insulator first. But why are metals not used as dielectrics?

[@DocSchuster]

That's exactly what's done! You've now made a much smaller-separation capacitor, where the dielectric is the insulator coating. Even better if this can be done in a liquid with an atomic-layer coating, no?

[@darthglowball]

Doc Schuster , thanks for the reply. I have another question that follows: I saw a chart which said aluminium foil has a dielectric constant of 10. Why not way higher? That doesn't seem near infinity. Also, I can't find any dielectric chart which list metals other than aluminum foil. Is there some big disadvantage with using a metal dielectric, like the electrons being too free and thus not being able to polarize in the neat way of electrons staying near their parent atom and just offsetting a bit?

[@curiousbit9228]

wonderful

[@resnickhalliday7913]

Dear Doc Physics , The shape of external field near the charged conductor altered because of induced charges on the surface of the conductor. The external field became zero inside the conductor. This called electrostatic shielding. often called a Faraday cage set up. The field is inside conductor is zero because of generation of another op-positional electric field inside the conductor that starts from from induced positive charges and ends at negative charges . This op positional electric field cancels the external electric field. Your video gave a reason that it is because energy is required which is not clear.

[@MysticMD]

Do you throw all those amazing notes away?! I hope you recycle them, at least. :)

[@DocSchuster]

I'm putting them into a box. Sometimes I get them out for class. I should probably laminate the ray tracing, even! It gets a lot of use.

[@thomasbutler5150]

Is Greg Okay? Did he ever turn around?

[@thomasbutler5150]

+thomas butler plz i need to kno

[@DocSchuster]

+thomas butler stuff got real.

[@thomasbutler5150]

Maybe hes dyslexic and it will be easy, also thank you for the videos.

[@RameshKumar-yy6hx]

Better one for explanation but sir, i don't like the way you use the paper, more clearly plzzzzz make best use of papers.

[@lynsikeye3714]

Am I the only one who hears Sheldon from BBT at 8:36? :D

[@sripavani6328]

u sound like deadpool. grt video

[@noureldinmohamed5395]

very helpful

[@emerckaraongi716]

Oh this is amazing

[@salwaaltahir988]

He's clearly enjoying himself teaching, hahaa

[@joaoa.7674]

You should use the conventions of major books, like Griffiths

[@DocSchuster]

Love me some Griffiths, but I'm just introducing this here (using Walker).

[@abdelouadoudreddahi6985]

goooood my frend

[@cannibol9009]

Nick Stegmeier: "If metal has "infinite polarizability", why not use it as your dielectric? Could someone help explain?" The answer is a dielectric is an insulator, whereas a conductor conducts. Thus, even though a metal has infinite permittivity, if one keeps a metal in between a capacitor it acts as a short circuit and pulls infinite current into it to satisfy Ohm's Law. The net Electric Field inside a metal is zero!

[@DocSchuster]

+cannibol9009 That's just what I was thinking.

[@manmohanbisht69]

Save pages . Use white board ..

[@diegotapiasilva7349]

you are hilarious, loved it

[@VS-ey2lf]

How you doing? good making a video for youtube you're funny doc

[@VS-ey2lf]

Was that your dad?

[@MrWarlock610]

Awesome!!!...0.0

[@Teppei9asone]

" And if k equals to 0," Sorry i mean infinity.

[@younessidbakkasse9742]

*Infinity Battery that will change the world*

[@SWiSHRoyal]

uhhhh, uhhhhh :D

[@grantstidham9322]

lol I was good up until teh lightining part \

[@th1alb]

you couldn't have explained this without doing a million complicated equations? i don't care about the math, i just want to understand the concept.

[@WhiteBeansYT]

That is literally some of the easiest math you will ever see when doing things like this. Sorry.

[@th1alb]

Wrong. This can be explained without math or with very little math. You're a typical "physics" person. Instead of talking about why the apple falls down from the tree (and not up) you rather spend the whole class about calculating what velocity it has at any given point, how long it takes to hit the ground, yada yada.

[@WhiteBeansYT]

Peter Gizmos I'm not going to argue with you - I just want you to know that almost every physics professor I've had has been a firm believer that you can't truly gain intuitive understanding of problems without understanding the math.

[@th1alb]

almost every physics professor = average i'm talking about elite. i would also argue the contrary.

[@th1alb]

Instead of going through a bunch of math, I would have been more interested in what happens if you take the dielectric out from the charged plates and place them between uncharged plates.