Topic 3: Gauss's Law Flashcards Preview

EE20085 Electromagnetics > Topic 3: Gauss's Law > Flashcards

Flashcards in Topic 3: Gauss's Law Deck (16)
Loading flashcards...
1

What is flux? 

It is helpful to imagine electric flux radiating from a point positive charge, hence the charge is a source of electric flux.

  • Between the two point charges, there are lines of electric field, E, and we can imagine these lines replaced by tubes of electric flux(Y) Coulombs.

2

The electric flux density?

The electric flux density D can be given by Y/A, where A is the cross-sectional area of the flux density. 

3

The equation for electric flux density(D)

For this to be true the electric flux must pass normally through, that is at right angles to, the cross-sectional surface.  Hence,

Y = DA

Where A is the perpendicular cross-sectional area and A is the flux density. 

4

Illustration of electric flux?

5

The relationship between electric flux density and electric field?

Electric flux density(D) is directly proportional to electric field(E)

6

The relationship between the electric field and density through surface integrals?

where D.ds is the vector dot product

7

Calculating the vector dot product D.ds?

D.ds = |D|.|ds|.cosØ

The surface integral of D with respect to ds, where D.ds is the total electrical flux crossing the surface S 

8

The total electric flux connecting two charges can be given by?

9

Gauss' Law

The electric flux passing through any closed surface is equal to the total charge enclosed.

10

Electric flux density in a sphere?

If S is a sphere, then by symmetry D is the same over the surface

11

The equation for Q, D and E when dealing with a sphere?

12

General equation for Electric flux density in air or vacuum?

D = e0E

13

General equation for electric flux density in linear isotropic materials?

D = e0erE

14

The E field and D for a cylinder?

The E field can be found through Gauss Law

The surface:

15

The E field and Gaussian surface can be calculated:

16

The electric field produced by a charge Q which is uniformly distributed over the surface of a thin spherical shell of radius a.