Physics 233. Review for exam I.

1. Chapter 23. Electric Charge.
• Unit: Coulomb
• Unit: C/s=1 Amp (for current, I)
• Charges come in discrete pieces; electrons, protons.
• Ways to charge objects:
• rubbing
• conduction (contact with another charged object)
• induction (bring another charged object close)
• photoionization, chemical dissociation
• Coulomb's Law:
• E-field Definition:
• Rules of Electric field lines. (eg. never cross)
• Field due to point charge:
• Field above or below a Electric Dipole: (SKIP)
• Hints for finding E - Shell theorems.
1. E-field outside of a spherically symmetric charge distribution is the same as the E-field of a point charge with the same total charge placed at the center
2. E-field everywhere inside of a shell with a spherically symmetric charge distribution is 0.
• Field Due to Continuous Charge Distributions.
• Line charge, C/m.
• Surface charge, C/m.
• Volume charge, C/m.
• Find or or
• Find
• Use symmetry to see if some components of are 0.
• Integrate
2. Chapter 24. Gauss' Law.
• Flux,
• .... the integral is over any closed (Gaussian) surface
• A gaussian surface is useful if:
• it is parallel and/or perpendicular to the E-field.
• E = 0 on the surface
• E is constant on the surface
• it intersects the point P where we want to find E
• Examples of E-fields we derived:
• Near a uniformly charged sheet/plane:
• Near a conducting plate with the charge density on both sides:
• Electric field outside spherical shell of total charge q:
• Electric field near a line of charge:

3. Chapter 25. Electric Potential.
• Electric Potential Energy.
• Relative
• Absolute and
• Units: J
• Electric Potential, .
• Relative
• Absolute
• Units: J/C or Nm/C
• Finding Potential from .
• Finding from Potential.
• ; ;
• When is uniform,
• Example: checkpoint 6.
• Potential and Potential Energy Due to Point Charges
• Example: Question 3, 10.
• Potential due to continuous charge distributions
• Potential is constant inside of conductors