1 / 8

§2.4 Conductors – capacitance

§2.4 Conductors – capacitance. Christopher Crawford PHY 311 2014-02-14. Outline. Exam on Monday question types, review sheet Conductors vs. dielectrics Charge, field, and potential Induced charge Electrostatic presure

heathermason
Download Presentation

§2.4 Conductors – capacitance

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.

E N D

Presentation Transcript

  1. §2.4Conductors –capacitance Christopher Crawford PHY 311 2014-02-14

  2. Outline • Exam on Mondayquestion types, review sheet • Conductors vs. dielectricsCharge, field, and potentialInduced chargeElectrostatic presure • CapactitorsField lines, equipotentialsCapacitance = flux / flowEnergy = flux x flow

  3. Exam – 4 questions • Calculate vector derivatives • Curvilinear coordinates • Integrate electric field or potential over a charge distribution • Parametrize surface, path or volume • Differentiate between r, r’, r_script • Split integrals and factor out x, y, z • Proof of relationships betweenfive formulations of electrostatics • See study sheet • Essay question – prose and diagrams • Relation between field, flux/flow, sources,especially applied to electrostatics • Geometric interpretation of laws

  4. Plotting field lines and equipotentials

  5. Conductors vs. dielectrics • Conductor • Free vs. bound charge • metal: conduction band electrons, ~ 1 / atom • electrolyte: positive & negative ions • Electrical properties of conductors • Field, potential, charge distribution • Coefficients of potential, capacitance

  6. Induced charges • Induction in a conductor – displacement of charge • Charge shifts until electric field is normal to surface • Surface charge terminates electric flux lines inside the conductor • Total charge remains constant unless there is an escape path • Faraday cage – shields external flux inside a hollow conductor • field lines from charge inside a hollow conductor are “communicated” outside the conductor by induction (compare: displacement field, 7.3)

  7. Electrostatic pressure • Force due to electric field on induced charge in conductor • Force per unit area: f = P (or electrostatic pressure)

  8. Capacitor • Pair of conductors held at different potential • Electric flux: • Electric flow: • Capacitance: Q = C ΔV • Parallels later in the course: • resistance, reluctance, inductance • Stored energy: E = ½ Q ΔV

More Related