Lecture04_Kim.pdf

# Lecture04_Kim.pdf - 1/19/2012 1 Lecture 4-1 Gausss Law:...

This preview shows pages 1–2. Sign up to view the full content.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 1/19/2012 1 Lecture 4-1 Gausss Law: Qualitative Statement (Review) s Form any closed surface around charges s Count the number of electric field lines coming through the surface, those outward as positive and inward as negative. s Then the net number of lines is proportional to the net charges enclosed in the surface . Lecture 4-2 Electric flux (Review) # of field lines N = density of field lines x area To state Gausss Law in a quantitative form, we first need to define Electric Flux. Surface can be of any shape Surface can be open or closed Must specify which way N E A E An = ch ch i E E An ca area=A = A cos if A is tilted A Lecture 4-3 Electric flux through Arbitrary Surface General definition of electric flux: E S E n dA = ch i (must specify sense , i.e., which way ) E E An = ch i Divide the surface into many very small, nearly flat plaquettes and sum over the contributions from all of them. Lecture 4-4 Electric Flux through Closed Surface E n a i E S E ndA = ch i I This integral is over a CLOSED surface. Since is a scalar product, the electric flux is a SCALAR quantity The integration element is a vector normal to the surface and points OUTWARD from the surface. Out is +, In is - n E Net # field lines going outward So, deforming the surface (such as shown) makes no difference!shown) makes no difference!...
View Full Document

## This note was uploaded on 02/05/2012 for the course PHYS 241 taught by Professor Wei during the Spring '08 term at Purdue University-West Lafayette.

### Page1 / 5

Lecture04_Kim.pdf - 1/19/2012 1 Lecture 4-1 Gausss Law:...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online