db_lec03_post

# db_lec03_post - PHYS 221 Lecture 3 Last lecture E field For...

This preview shows pages 1–7. Sign up to view the full content.

PHYS 221 Lecture 3 • Last lecture: E field • For a point like charge • For any charge distributions • Today we look at another way to determine E 1/17/12 1 E = F q 0 F = k q 0 q 1 r 2 ˆ r D. Bortoletto PHYS221 E = k q 1 r 2 ˆ r E = k dq r 2 ˆ r

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

View Full Document
1/17/12 2 Gauss Law *relates the electric fields at points on a closed Gaussian surface and the net charge enclosed by that surface. What are in the boxes? D. Bortoletto PHYS221
1/17/12 3 Concept of Flux θ v Air stream with uniform velocity, v , flows through a loop of area A Φ = volume time can define a flux: D. Bortoletto PHYS221

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

View Full Document
1/17/12 4 Flux of an Electric Field area lines of number ~ E EA ~ lines of number area Works only when lines are perpendicular to surface! Need to quantify the pattern. More lines comes from the box – more charge inside! Q: What is the number of lines that cross the surface? Electric field is proportional to the number of lines per unit cross-sectional area: D. Bortoletto PHYS221
1/17/12 5 Flux of an Electric Field Analogy : think of rain which falls into a bucket. Less rainwater enters the bucket if it is tilted A E EA EA = = θ cos ~ lines of number The number of lines crossing a surface is proportional to the perpendicular component of the field. Definition of electric field flux: cos EA A E EA E = = = Φ D. Bortoletto PHYS221

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

View Full Document
1/17/12 6 Electric field flux Field lines can either enter the closed surface area, or exit it.
This is the end of the preview. Sign up to access the rest of the document.

## This note was uploaded on 02/05/2012 for the course PHYS 221 taught by Professor Pyrak-nolte,laura during the Spring '08 term at Purdue.

### Page1 / 20

db_lec03_post - PHYS 221 Lecture 3 Last lecture E field For...

This preview shows document pages 1 - 7. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online