Insights Blog
-- Browse All Articles --
Physics Articles
Physics Tutorials
Physics Guides
Physics FAQ
Math Articles
Math Tutorials
Math Guides
Math FAQ
Education Articles
Education Guides
Bio/Chem Articles
Technology Guides
Computer Science Tutorials
Forums
Intro Physics Homework Help
Advanced Physics Homework Help
Precalculus Homework Help
Calculus Homework Help
Bio/Chem Homework Help
Engineering Homework Help
Trending
Featured Threads
Log in
Register
What's new
Search
Search
Search titles only
By:
Intro Physics Homework Help
Advanced Physics Homework Help
Precalculus Homework Help
Calculus Homework Help
Bio/Chem Homework Help
Engineering Homework Help
Menu
Log in
Register
Navigation
More options
Contact us
Close Menu
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Forums
Homework Help
Introductory Physics Homework Help
Why is this equation from Purcell's EM textbook correct?
Reply to thread
Message
[QUOTE="Leo Liu, post: 6525123, member: 660839"] [B]Homework Statement:[/B] . [B]Relevant Equations:[/B] . I saw the following equation on page 31 in Purcell's EM textbook. $$F=\epsilon_0\int_{E_1}^{E_2} E\, dE=\frac 2 {\epsilon_0} (E_2^2-E_1^2)$$ Here, F is the force on a unit area. And then he claims that since ##E_2-E_1=\sigma/\epsilon_0##, the equation can be further simplified to $$F=\frac 1 {\epsilon_0}(E_1+E_2)\sigma$$ However, I think the correct coefficient in the last part of first equation should be the inverse of what it is now (##\frac{\epsilon_0}{2}## instead), as only then can I obtain the second expression. I have no idea why the author wrote the equation this way. To give it a little bit of background, dE is the change in the electric field of a thin layer of a charged sphere, E1 is the the electric field inside, and E2 is the electric field outside. Could someone explain? [/QUOTE]
Insert quotes…
Post reply
Forums
Homework Help
Introductory Physics Homework Help
Why is this equation from Purcell's EM textbook correct?
Back
Top