Topics covered on Exam 3

Chapter 23

  1. conductors: at surface electric field is perpendicular to surface
  2. Gauss's Law: surface of a conductor

Chapter 24

  1. path integral of E to define electrostatic potential difference ΔV (applied this to field from point charge).
    Two ways to make a path integral managable:
    1. Make path go along, then perpendicular to field.
    2. When field components are given as functions: integrate a path that moves parallel to the axes, one at a time.
  2. equipotential lines/surfaces
    1. perpendicular to electric field lines
    2. density corresponds to field strength
  3. equation for V of point charge, using the standard choice of V=0 at infinite distance away
  4. potential V due to several charges: superposition
  5. finding V=0 places near oppositely charged points
  6. V constant (but not zero!) inside spherical shell
  7. V constant inside conductors (conductors are equipotentials)
    1. Can use this to find the distribution of charge between connected conductors
  8. moving one charge amongst others. ΔU=qDV.  new unit of energy eV
  9. problems involving energy conservation
  10. "potential energy of assembly" means U of a configuration of multiple charges; sum over all pairs
  11. object integrals to obtain V at a point due to one-dimensional extended objects (straight rod, ring)
    1. Special case: when all of object is same distance from point, can just use point charge formula
  12. object integrals to obtain V due to two-dimensional extended objects (e.g., disk)
  13. we CANNOT choose V=0 at infinite distance for objects that are modeled as "infinitely large" (long lines or sheets of charge)
  14. derivatives to get E field (magnitude or vector components) from potential V(x,y,z)

Chapter 25

  1. capacitors, defining equation of capacitance
  2. parallel-plate capacitors: capacitance determined by shape
  3. capacitors combined in parallel and in series
  4. charge and potential in capacitor combinations (especially "inside" a network)
  5. changes when capacitor connections are changed
  6. changes when capacitor shapes are changed
  7. permittivity of materials, dielectric constant
  8. potential energy in charged capacitor
  9. energy density due to electric field
  10. Gauss's Law adjustment with dielectric: either consider all charge (including charge induced on dielectric), OR consider only the free charge and multiply the ε0 by the dielectric constants present

Chapter 26

  1. drift velocity and Current
  2. restrictions on current flow; current in = current out
  3. Ohm's Law and Resistance
  4. current density J
  5. current as a flux of current density (including integration of non-uniform current density)
  6. resistivity
  7. power dissipation by resistors ( P = i V , etc.)