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Electric field | Electric charge, electric force, and voltage | Physics | Khan Academy

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We can think of the forces between charges as something that comes from a property of space. That property is called the electric field. Created by Sal Khan.
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Physics on Khan Academy: Physics is the study of the basic principles that govern the physical world around us. We'll start by looking at motion itself. Then, we'll learn about forces, momentum, energy, and other concepts in lots of different physical situations. To get the most out of physics, you'll need a solid understanding of algebra and a basic understanding of trigonometry.
About Khan Academy: Khan Academy offers practice exercises, instructional videos, and a personalized learning dashboard that empower learners to study at their own pace in and outside of the classroom. We tackle math, science, computer programming, history, art history, economics, and more. Our math missions guide learners from kindergarten to calculus using state-of-the-art, adaptive technology that identifies strengths and learning gaps. We've also partnered with institutions like NASA, The Museum of Modern Art, The California Academy of Sciences, and MIT to offer specialized content.
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Опубликовано:

27 авг 2024

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Комментарии : 231

@YassinHM 3 года назад

I watched this nearly 10 years ago, and 10 years later it is just as invaluable if not more given the current global condition. Thank you Sal. Donated :)

@Ragd0ll1337 13 лет назад

Dude, Sal, I don't know what it is about your voice but man it's really easy to pay attention to your voice. You have a pretty cool voice. :P

@ericzhou1028 4 года назад

Ragd0ll ok boomer

@samuraijosh1595 3 года назад

@@ericzhou1028 Ok, Mr. Unfunny.

@misslolipopluvscandy 3 года назад

bro my thoughts exactly

@duketristian9463 3 года назад

i dont mean to be off topic but does anybody know a way to log back into an Instagram account..? I stupidly forgot my login password. I love any help you can give me!

@rexkaiser7013 3 года назад

@Duke Tristian Instablaster =)

@danielmattera4298 9 лет назад

these are literally saving my grade right now....

@pokemaniac333 9 лет назад

I don't know if anyone's pointed it out yet (and it's not a big deal because the concept is spot-on) but around six minutes in, Sal says the E-field is 2500, but it should be 2250.

@dolphinsatsunset1 9 лет назад

Demon519 you're correct. because 9 / 4 = 2.25 but then when you multiply that by 10 ^ 3 it becomes 2250 Newtons

@handeerdogan5107 7 лет назад

still 2250, isnt it?

@n7pako367 7 лет назад

you are correct, girlfriend

@qimingzhang8803 7 лет назад

Demon519 yeah that was funny hahaha

@ankushmoger7737 6 лет назад

I agree

@strangeturtle5947 8 лет назад

This might save my physics grade. Get back to you after tomorrow's exam.

@pero828 8 лет назад

+Sandra Faye Villagarcia Did it?

@strangeturtle5947 8 лет назад

It sure did. :D

@HIJT2FAUTIKA 7 лет назад

Fangirl Faye A lot of the stuff that I learn in my physics class isn't even on youtube which sucks lol, I'm just here for the heck of it

@zain4019 7 лет назад

Fangirl Faye YOU GIVE ME HOPE! I also have an exam :)

@alexander324324 11 лет назад

I hope in the future only good teachers like you teach, that way student will be able to learn more efficiently.

@a4194 Год назад

I hope your dream come true someday but we still don't have teachers like him

@surostig 13 лет назад

This was an excellent video. Most certainly bolstered my understanding of the concept; also definitely taught in a very intuitive and meaningful manner.

@niconikko 12 лет назад

The way I gain knowledge about an unknown topic is through Khan. If I think I can move on to the next level, that's the time I will tackle free lectures from the Universities like MIT or something, because I find their approach more general. But overall, without Khan, I have no bridge to higher thinking.

@vhapniphysics 6 лет назад

Khan Sir, first day when I watch your videos I was surprised that how one can write in this way .....digitally...and today I am using it perfectly..this is because of you ...Thankful to you for this reason...

@amazingconcepts4527 6 лет назад

Dr Sushil Kumar Guruji so can you tell me how to write?

@islamisthebestreligion1738 6 лет назад

Your kidding right?

@chooha 5 лет назад

@@islamisthebestreligion1738 😂😂😂😂

@shamiqthedev3322 2 года назад

It is the end of 2021 December, It is still useful, can't thank enough you have done a brilliant work bro!

@Dyslexic-Artist-Theory-on-Time 10 лет назад

It is odd that we have all the mathematics, but we have no objective understanding of what charge is!

@GordonNFleming 8 лет назад

+An artist theory on the physics of 'Time' as a physical process. Quantum Atom Theory In mathematics we study precise relationships and patterns. In science we study the relationships and patterns of nature and while we do acquire objective understanding of objects in nature, that understanding is never ultimate or final.

@mistakenmeme 6 лет назад

Well, there more of a tool to aid us in math.

@alektad 10 лет назад

the right answer is 2250 N/C, great lesson, thanks.

@siyuliao2923 7 лет назад

Em, just want to say that 9×10^3÷4=2250. It is very helpful, though

@Gekkou31 8 лет назад

I'm supposed to be learning this, and im too busy rewinding and laughing at "SQUALER"

@rin.rin.3024 7 лет назад

At what time? I missed that lol

@samuraijosh1595 3 года назад

@@rin.rin.3024 did you find the timestamp.?

@PandaBlooket Месяц назад

@@rin.rin.3024 4:14

@zadock6 13 лет назад

Please, never stop your videos. Good didactics is so unbelievably rare and you are doing a great job in this field. thx for that

@Name-bb8wo 2 года назад

youtube is filled with these videos nowadays :p

@pastuh 3 года назад

this guy knows everything :)) what i search, this dude all the time appears..

@zain4019 7 лет назад

The mouse wriggling everywhere across the screen makes it seem like sal is having a seizure during the whole video XD

@JoeOf91 12 лет назад

could someone explane to me why that -1C, didn't make the final anawer -2500? how does writing the formula F= q*E change the negative sign?

@MindZiper 13 лет назад

Sal, it's 2250N, not 2500. Make sure to post a note in the video so this doesn't confuse someone (like it did to me :P). Thanks for the video!

@skylar011 2 года назад

Really wish you would redo some of these with your new and improved graphics software :/

@teezyjbaby08 11 лет назад

CORRECTION...at 6:15; the E should be 2250 N/C; (9*10^3)/4 = 2250 not 2500

@Elevatone 11 лет назад

I just commented in the last video about the ambiguity between using d and r! Thanks for clearing that up. Your awesome.

@GotKingKongBallzz 14 лет назад

You are one of the best teachers I have ever heard, and I don't even know what you look like!!

@SLHappyEmo1001 11 лет назад

I think that's one of the main reasons he's so popular. Even youtube automatic captions gets it right most of the time!! Now that's an achievement!!

@jasonvegan5761 9 лет назад

SQUALER!!!!!!!!!!!

@riowatson3574 6 лет назад

I don't know why I laughed so hard when he said "squalar" lol

@acaciocorreia4380 6 лет назад

I'm very thankful for these videos, they are very interesting and easy to follow. However, I was wondering why the quality (in terms of resolution and drawings) is so low in some videos.

@thomas99971 5 лет назад

Published 11 years ago

@peachboy595 12 лет назад

I like how he doesn't forget anything that would confuse us

@Xclann 13 лет назад

Just making sure... E = Electro Motive Force = Voltage = Electric Field? Thanks ..

@ATMfromNJ 13 лет назад

2 people aren't smart enough to see the value in these videos! GREAT WORK Teach!

@Be1smaht 12 лет назад

he/she did it for those trying to follow along while he does the math.... thanks dude !! :)

@tanyatanteta1801 3 года назад

Thank u very much, Sir. Your short videos literally made more sense than what I'm reading

@Pwise003 11 лет назад

Because Force it's self is a vector quantity, for example Newtons second Law states that F=m * a. In relation to electrostatics it is stating that F= q * E with q being charge and E being the field. Well when the ATTRACTION OR REPULSION of each charge has a magnitude and a DIRECTION, thus being a vector quantity, because if it just had magnitude it would only be a scalar quantity. Hope that helped.

@iz.m.7560 9 лет назад

I really appreciate the content but man, did you record that with a hairdryer? Pixels. Pixels everywhere.

@danielwest9976 8 лет назад

IKR‽‽‽ its like it was made 8 years ago or something!

@luked4043 7 лет назад

Iz. M. Well if it was higher res there's actually be more pixels?

@bilbobaggins8877 3 года назад

Why do we consider the negative sign 13:10 when in the initial formula for force we were taking the absolute value?

@TheBubblerella 6 лет назад

"I should actually use a line tool...", "...but then i can't draw the arrows..." LOL so cute.

@Flemgren 12 лет назад

My brain can comprehend this amount of information. It is like a lecture without the bullshit

@mihiro271 13 лет назад

awesome explanation . very informative for beginners !!! good job

@ThaRealJman 11 лет назад

I'm pretty sure you could take over the world with your knowledge if you wanted to.

@DebadyutiBhattacharya 9 лет назад

9÷4=2.25

@zahidyaka 6 лет назад

Wish I though of watching these videos before the test and not after. :(

@TayMon999 10 лет назад

Funny when he keep saying "I don't know" and then put a number

@PandaBlooket Месяц назад

4:14 "Squalar" XD

@ArifulIslamPalash 11 лет назад

Well, I must say you are having my attention somehow... Superb ! Thumbs Up !

@smpsn 13 лет назад

this is awesome thank you soooo much...im a 43 year old who is studying for stage one physics exam next week...job well done:):):):):)

@tedhanley1706 6 лет назад

I am curious about something. At 9:17 in the explanation of field lines around Q, you say, "as you get closer to the source of the electric field the charge gets stronger" I did not know the charge gets stronger or weaker. I thought a charge was a charge, multiples of either negative or positive increments and was fixed. How does the charge get stronger? Does it accumulate more electrons?

@zoranhacker 5 лет назад

The charge doesn't actually get stronger, the electric field does

@aresdude 14 лет назад

My physics professor, Professor Wolf at Cooper Union told us that is a common misconception that more dense field lines means a stronger electric field. Good video though!

@RAIDENM4N 4 года назад

Do Electric Fields only work with Static Electricity, or does it occur in current as well?

@NewyJimmy 14 лет назад

u rock my world, ur getting me through uni, in fact stuff uni when i have khan academy

@calemlinke5130 4 года назад

what about spherical shape? the world around us IS three dimensional... perhaps bringing up the equation to cause 3d effects?

@onelenkangezi6988 3 года назад

with this channel,i can skip all my physics class

@tnagan 15 лет назад

Sal you are awesome. Thank you so much for what you do for us!

@zakirhussain-js9ku Год назад

What is electric field made of? How electric force acts w/o contact.

@madhavapaliyam2734 7 лет назад

So helpful, much more helpful than barron's book or anything of that sort.

@AhmedMohamed-ei6tc Год назад

It's an amazing and enjoying explaination

@jonc925 6 лет назад

As soon as I heard him say squaler, I scrolled down to see the comments hoping someone commented about it, and low and behold, a comment had been made! Another win for the YT community.

@PPxrare 13 лет назад

Is there a video which explains Gauss's law ?? can someone please link the video for khanacademy if there is one, or just give me the link to a video which they thought explained gauss's law properly?

@qualquan 9 месяцев назад

REAL definition of Electric Flux = NUMBER of acceleration lines (AL) produced by charges travelling at light speed. Electric Field (E) = ACCELERATION = number of AL/Area = Density of AL. That's all.

@atyra92 13 лет назад

you've done a really great jobs ! thumb up

@ismaelochoa8730 7 лет назад

I have seen a definition of field strength = F/Q, but why is that? why not F/(2Q)? or F/Q2?, is this word "strength" related to stress-strength as in mechanics?

@MrChin000 13 лет назад

At 5:59 the electric field at that point is = (9 x 1000) / 4 = 2250 Newtons per coulomb not 2500. Kinda insignificant but just pointing it out lol. Awesome video man.

@SevenDeMagnus 4 года назад

Cool. What's the difference between an electric field & electricity?

@learningcommunist5502 Год назад

The fact that this video's length (13:32 )is the same as the previous is just strange...

@Hazal6698 2 года назад

very very very good explanation sir

@gracetran 13 лет назад

@ShankMasterKank LOL omg i thought i was the only one. i really like his voice!

@marinmb44 13 лет назад

khan . . does the electric field vector fall off to a certain limit? In other words, do the vectors converge?

@ZackSussmanMusic 6 лет назад

ah this finally makes sense now, thanks!

@mayankukani9600 6 лет назад

Content is awesome as always just not happy that i cannot go beyond 240p.

@MrSukhpreetbal 13 лет назад

thanx alot AY GOD GIVE U ENERGY MORE THN U CLARIFY ENERGY CONCEPT TO US

@sandiptiwari5797 7 лет назад

I have seen all the vedios ...and I want to see some more vedios to make my concept clear......

@bonganipeter9433 Год назад

This is a clear explanation

@qtubber 11 лет назад

In the exercise why is -q? The charges must attract each other?

@colonelbastian6036 9 лет назад

this is a great lecture

@vladpinera9035 8 лет назад

i learn more on the comments section... but i thank the vid still... if it weren't for the tree there would be no fruit.

@bobu5213 4 года назад

So is E the electric potential energy?

@matijakukec4731 6 лет назад

I still can't get it how is he able to write those equations with mouse only 👏👏👏👏👏

@raecooker 5 лет назад

So electric field can never be negative? How does is show direction then?

@gopesh97 10 лет назад

what will be the pattern of electric field lines if we consider a dipole..

@mansimanhas 11 лет назад

why force between 2 charges is a vector quantity ???????? what happens with the direction...???? plzzz plzz explain ?????

@mistakenmeme 6 лет назад

Oh, it basically tells you whether the charges equal or opposite. The two most important directions are: Out and in.

@sammy5576 4 года назад

thanks, Sal is awesome!!!

@drettlinking 5 лет назад

I thought it was E=kQ/r... because if E=Work/Charge, and Work is equal to Force Times distance... then if you derive it in this way, you shoud get E=kQ/r instead of E=kQ/r^2

@GospodinJean 5 лет назад

"the charge times the electric field is great in you" - Yoda, Master

@12manganime 12 лет назад

wat does AP mean? advanced placement? is that like higher level?

@nanakwameasiedu-amponsah1405 4 года назад

When he says electric field, does he mean electric field density ? Just wanted clarification

@sajdsjdsjkgds 11 лет назад

it will have no effect since they are neutrons and thus are neutrally charged

@LtThompsonCS 11 лет назад

@ 6:30, shouldn't it be 2250 N/C??

@izpotter 6 лет назад

I really cant understand this...too difficult!

@diy-projects 5 лет назад

i like the video but there was really nothing discussed about voltage in this vid

@blkjedi954 15 лет назад

awesome vids, but you probably should outline what you're gonna talk about beforehand. Sometimes it sounds like you're rambling, you go in one direction, then another, then you comeback. Its a tad irritating. I subscribe to you b/c you provide an alternative point of attack of the subject matter which is deeply appreciated and helpful. But try and remain focus when imparting material that is somewhat slippery to grasp. Thank you. p.s. - Great job overall!

@For_us79 11 месяцев назад

The vedio's age = my age 🙂

@KaushikMishrakk 9 лет назад

At 10:30 Why when a positive and negative charged object kept close for Interaction the direction of the lines go from positive to negative?

@pokemaniac333 9 лет назад

Kaushik Mishra It's really just convention. I suppose it's because we consider protons to have mass, and electrons have negligible mass, so when the two are attracted, the electrons tend to do the majority of the motion, so we say the field lines come from positive. That's my best guess. Again, it's just convention.

@pokemaniac333 9 лет назад

Kaushik Mishra Actually, given more thought: by convention, we assume the E-field is how a positive charge would be affected. The electric field can be thought of as the path a positive charge that we arbitrarily insert, would go. As such, it is repelled by the positive charge and attracted to the negative charge. Hope this helps!

@KaushikMishrakk 9 лет назад

Demon519 thanks. meanwhile even i got something - its actually with accordance to the direction of current and as its said that positive terminal has more potential than that of the negative terminal hence according to the concept of electric potential it flows from higher potential to lower potential in our case from positive to negative . but m not sure of the fact why positive terminal is considered to have higher potential.

@ccmiint 8 лет назад

+Kaushik Mishra The positive terminal doesn't have a higher potential than the negative terminal. The positive terminal lacks electrons and the negative terminal has plenty. They both are equal. A 9v battery has +9 at the positive and -9 at the negative terminal. Arbitrarily, a positive test charge (i.e. a proton) was chosen to create the electric field line diagram so we can visualize and assign direction to charge. And it's become a convention in physics. No other reason but by choice. So what this means is that when a proton goes near a proton they will repel and when a electron goes near a proton they will attract.

@GordonNFleming 8 лет назад

+Kaushik Mishra That the electric field always points in the direction of the force it will exert on a positive charge is a pure convention that was adopted long before we knew of the existence of protons or electrons, back in the 19th century.

@nilaij 11 лет назад

At 6 mins the electric field is 2250 N/C rather than 2500. Great video btw

@nukingthemoon9251 3 года назад

(9*10^9*1*10^-6)/4 = 2250. Use a calculator during the video if you want to or plan your lesson, but get your stuff right!

@SamRobertduty 16 лет назад

Yes physics ! Thanks for the vid^^.

@Donaldbeebi 5 лет назад

his voice

@villamodel 6 лет назад

at 3:32 where does the -1C go?

@mostafaahmednasr621 6 лет назад

What if the charge rotates

@FasAntick 6 лет назад

There are so many different equations for electric fields ahh

@PIRACADEMYFORPHYSICSBYPIRSIR 5 лет назад

Sir khub valo laglo

@tripunk 8 лет назад

can someone explain why the fields are curved? I've watched it a few times and didn't catch that if he mentioned it

@Chopperaemon 7 лет назад

+A. L. As the electrostatic line moves up that force is attracted to the negative one and a curved line is appeared... I think so

@14Ramjet 7 лет назад

Not sure if you got this answered, but it will help other people. Think of the lines not much as a solid curve but a bunch of vectors. The vectors show the magnitude and direction of the electric field lines and where they are attracted to, which will then make the shape of a curved line.

@tripunk 7 лет назад

Ramjet14 Thank you - but why do all those vectors make curved lines?

@Chopperaemon 7 лет назад

A. L. Those are the tangent lines of force which gives the direction of the electric field at that point😊