## Lecture 3: Electric Flux, Gauss's Law, Examples

author: Walter H. G. Lewin, Center for Future Civic Media, Massachusetts Institute of Technology, MIT
recorded by: Massachusetts Institute of Technology, MIT
published: Oct. 10, 2008,   recorded: February 2002,   views: 86378
released under terms of: Creative Commons Attribution Non-Commercial Share Alike (CC-BY-NC-SA)
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# Description

"Today we're going to work on a whole new concept and that is the concept of electric flux. We've come a long way. We started out with Coulomb's law. We got electric field lines. And now we have electric flux.

Suppose I have an electric field which is like so and I bring in that electric field a surface, an open surface like a handkerchief or a piece of paper. And so here it is. Something like that. And I carve this surface up in very small surface elements, each with size DA, that's the area, teeny weeny little area, and let this be the normal, N roof, the normal on that surface.

So now the local electric field say at that location would be for instance this. It's a vector..."

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1 Abhishek Kumar, December 31, 2008 at 8:22 a.m.:

thats a great video thanks sir

2 mohamed, February 24, 2009 at 6:34 p.m.:

thanks professor for this great work..i am a student at engineering faculty (Egypt)..
i am asking if there anyone with whom we can share the knowledge about physics??

3 gina sucayan, July 22, 2009 at 4:32 p.m.:

can u answer this questions for me?

"Surface charge densities of 200,-50 and psxµC/m2 are located at r=3,5, and 7 cm respectively. find D at r=4cm? find psx if D=0 at r=7.32 cm?

thanks. ill wait for response. i'll just find it hard to solve.

4 Mukesh Dhnadia, July 25, 2009 at 12:47 p.m.:

It's Superb. Not any comments or not a sigle word to describe this lecture.

It's wonderful and too much effective.

5 Rajendra Kumar Agrawal, September 25, 2009 at 6:02 p.m.:

Respected Sir,

Professors like you inspire us to live Physics,breathe Physics.Your lecture make us believe-"Physics is beautiful".

regards

R.K.Agrawal

6 SunZhou, September 26, 2009 at 10:56 a.m.:

Thank you sir,that's a really good lecture.
I'm a student at material engineering in China,I want to know if there's some websites we can share our knowledge about Physics. Thank you.

7 AWAIS MUNIR, November 4, 2009 at 3:29 p.m.:

I, student of class inter, am realy very impressed to respected sir WALTER g.h lewin because of his carismatic work in the field modern physics. His guidence is very use ful for students of all over the world, who are interested in the modern physics

8 BRIJMOHAN, November 30, 2009 at 6:05 p.m.:

sir,

9 Kevin M., December 28, 2009 at 11:20 p.m.:

I'm a junior mechanical engineering major. Having taken this class as a freshman, I now realize why MIT is so selective and expensive. I'm taken aback at the amount of content this course covers per lecture, the gift Dr. Lewin has for teaching, and the things I'm learning as I watch.

By putting these lectures on the Internet, MIT is giving the world an invaluable gift.

10 reuben, March 8, 2010 at 11:41 a.m.:

thanks for that lecture professor.am a student at kenyatta university.

11 LINGEREW GUADIE, April 8, 2010 at 3:27 p.m.:

I AM a STUDENT IN ADAMA UNIVERSITY IN ETHIOPIA THE DEPARTEMENT OF ELECTRICAL ENGINEERING.

THANKS FROFESSOR FOR YOUR POTENTIAL TO CERATE MANY APPLICATION FOR PHYSICS.

IF YOU HAVE ANY COMMENT
WRITE IN THIS E/MAIL

12 roja, December 16, 2010 at 4:14 a.m.:

sir give some physics videos for engineering students.

13 F M Farias, June 11, 2011 at 4:33 p.m.:

Prof. Lewin lectures are simply wonderful.

14 Kushagra Jetly, July 12, 2011 at 5 a.m.:

a really nice lecture sir
thanks a lot
i am a class 12 student in India preparing for iit and all your lectures really help me.

15 prasanta kumar behera, October 30, 2011 at 3:07 a.m.:

no comment

16 Amuri Mus, February 26, 2012 at 2:22 a.m.:

I'm a petroleum student at the University of Stavanger(Norway), i appreciate this lectures and sir himself

17 Mn, February 28, 2012 at 9:04 p.m.:

18 MP, April 6, 2012 at 7:26 p.m.:

I'm student of software engineering and I always be boring in physics lessons.If this man was my teacher,I would be in class every lesson.

19 waqas ahmad, December 12, 2012 at 8:45 a.m.:

the lectures of electricity and magnetism are perfect

20 rizwan butt, October 12, 2014 at 9:15 a.m.:

any one have english subtitles

21 Jhesus Legarda, March 14, 2015 at 9:55 p.m.:

This lecture was awesome .-

22 Md.Abu sad sayeed, January 18, 2016 at 8:26 p.m.:

sir , very nice lecture. Thanks a lot sir.