Closed integral in electromagnetics

AI Thread Summary
Gauss's Law relates the total charge enclosed by a surface to the closed integral of the electric displacement field (D) over that surface. The equation in question, which equates the total charge to the closed integral of D.ds, is a mathematical expression derived from Gauss's Law. The term Dr refers to the radial component of the electric displacement field, which provides context for the manipulation in the notes. The discussion highlights confusion over the clarity of the notes and the need for better explanations in the study materials. Overall, understanding the relationship between these concepts is crucial for mastering electromagnetics in engineering.
tidesong
Well I'm studying this under engineering but its also maths so I posted this here and hope its in the right forum

The question is: When using Gauss's Law i have this equation in my notes: total charge enclosed by surface = closed integral of ( D .ds) over S

the next line (in my notes) equates this to Dr( closed integral of dS over S)

Is this a mathematical manipulation, or is this due to some law? And is Dr just a constant or does it have some meaning? Thanks.
 
Engineering news on Phys.org
Ah thanks! If Dr is the radial component then it makes sense! I'm trying to guess what my notes mean too :P
 
Yeah! Our notes are so lousy! Thanks for helping out =)
 
Thread 'I need a concave mirror with a focal length length of 150 feet'

Thread 'I need a concave mirror with a focal length length of 150 feet'

I need to cut down a 3 year old dead tree from top down so tree causes no damage with small pieces falling. I need a mirror with a focal length of 150 ft. 12" diameter to 36" diameter will work good but I can't think of any easy way to build it. Nothing like this for sale on Ebay. I have a 30" Fresnel lens that I use to burn stumps it works great. Tree service wants $2000.
View full post »

Thread 'Questions about the Tesla turbine'

Hi all, i have some questions about the tesla turbine: is a tesla turbine more efficient than a steam engine or a stirling engine ? about the discs of the tesla turbine warping because of the high speed rotations; does running the engine on a lower speed solve that or will the discs warp anyway after time ? what is the difference in efficiency between the tesla turbine running at high speed and running it at a lower speed ( as fast as possible but low enough to not warp de discs) and: i...
View full post »

Similar threads

A Vanishing of an integral of a divergence over a closed surface
Replies
1
Views
1K
On which objects can we apply Gauss' Law to find the electric field?
Replies
10
Views
4K
Electric field is constant around charged infinite plane. Why?
Replies
4
Views
4K
Gauss' law problem -- Should the field due to both the inside and outside charges be taken into account?
Replies
28
Views
1K
I Multiple integral Jacobian confusion
Replies
7
Views
2K
I Pushing a rod in a magnetic field
Replies
15
Views
2K
Arriving at the differential forms of Maxwell's equations
Replies
3
Views
1K
I Is it possible to apply Gauss' law to a Klein bottle?
Replies
1
Views
821
Gauss' law in line integral, Q=##ϵ_0 ∮E.n dl=-ϵ_0 ∮∂ϕ/∂n dl##
Replies
2
Views
1K
A Stationary solutions to Klein Gordon equation in spherical symmetry
Replies
9
Views
2K

Hot Threads

Recent Insights

Back
Top