Physics: Electricity and Magnetism

Summary of Chapter 23 - 26

 

(image credit: http://hyperphysics.phy-astr.gsu.edu) <~ awesome website, btw!!!

Electric Fields

E = f / q

F = k[Qq/r^2]

Gauss's Law

Net flux:

 

Electric Potential

           (The following information on potential was pulled from this website:  http://physics.bu.edu/~duffy/semester2/c05_potential.html)

• The potential a distance r from a point charge Q is given by:

V = kQ/r

• Potential energy in a uniform field is U = qEd, so potential is:

V = U/q = Ed

 

d here is some distance moved parallel to the field, and is measured from some convenient reference point.  More important is the potential difference, which increases as you move in the opposite direction of the field:

DV = EDd  Even more generally:

DV = -E · Dr

Equipotentials

• Equipotential surfaces are always perpendicular to field lines.
• No work is required to move a charge along an equipotential.
• Equipotentials connect points of the same potential. They are similar to contour lines on a topographical map, which connect points of the same elevation, and to isotherms (lines of constant temperature) on a weather map.

Capacitance & Dielectrics