1 / 12

Fields and Waves

Fields and Waves. Lesson 3.1. ELECTROSTATICS - INTRODUCTION. ELECTRICAL CHARGES. SOURCE of Electrostatic E-Field is CHARGE. Examples of various charge distributions:. 1. Point charge - Q (units of Coulomb).

Download Presentation

Fields and Waves

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.


Presentation Transcript

  1. Fields and Waves Lesson 3.1 ELECTROSTATICS - INTRODUCTION Darryl Michael/GE CRD

  2. ELECTRICAL CHARGES SOURCE of Electrostatic E-Field is CHARGE Examples of various charge distributions: 1. Point charge - Q (units of Coulomb) - model individual particle (eg. Electron) or a well-localized group of charge particles 2. Volume Charge Density - ror rv (units of Coulomb/m3) - large # of particles - ignore discrete nature to smooth out distribution Eg. Doped Region of Semiconductor, e-beam in a cathode ray tube ( Beam has finite radius )

  3. ELECTRICAL CHARGES Other examples of Charge Distribution…….. 3. Surface Charge Density - ror rs (units of Coulomb/m2) Eg. Very thin charge layer on conductor surface 4. Line Charge Density - ror rl (units of Coulomb/m) - not as physically realizable Eg. Model for a wire, electron beam from far

  4. ELECTRICAL CHARGES Maxwell’s equation: More generally, Derived from: or Do Problem 1

  5. COULOMB’S LAW (force), between point charges Q1 Unit vector in r-direction Force on Charge 2 by Charge 1 R Q2

  6. COULOMB’S LAW - E Field ,of Q1 is Unit vector pointing away from Q1 Then, - we work with E-Field because Maxwell’s equations written in those terms

  7. Point charge E-FIELDS , is a VECTOR Field How do we represent it? - Field points in the direction that a +ve test charge would move Represent using Arrows : Direction and Length Proportional to Magnitude or strength of E-Field

  8. +Q y x -Q E-FIELDS Computation of E-fields from multiple charges: Example: DIPOLE - 2 separated opposite polarity point charges Apply superposition of Fields Planes of symmetry: Horizontal axis: Ex cancels, Ey adds +Q vector Vertical axis: only Ey component -Q Resulting vector

  9. E-FIELDS - Some examples

  10. E-FIELDS - Some examples

  11. E-FIELDS - Dipole

  12. E-FIELDS How would the DIPOLE field lines change if the charges were the same polarity? APPLICATION of SUPERPOSITION • Usually text has many examples of setting up this integral • In the course we will do some discrete Scases Do Problem 2

More Related