Electric Fields

Electric Fields

1. Coulomb's law= force between charges in a vacuum

   • F= 1Qq/4pier^2
   • electrostatic force directly proportional to the product of the charges
   • Electrostatic force inversely proportional to the square of the distance between them

2. Electric field Strength

   • electric field strength E as force per unit positive charge = F/Q
   • representation by field lines
   • Radial Fields vs uniforme Fields
     • E radial=1Q/4pier^2
     • E=V/d
   • represented by field lines
     • go from positive to negative

3. Electric Potential

   • the electric potential at a certain point in a field is defined as the work done per unit positive charge when it is moved from infinity to that point
   • JC-1= V

4. Comparison of electric and gravitational fields

   • Similarities
     • follow inverse square law
     • field lines are parallel and in the same direction
     • Force is proportional to the product of two masses or the product of the two charges
     • field strength and potential difference have similar definitions for electric and gravitational fields
   • Differences
     • masses always attract- some charges repel
     • electric acts on charge, gravitational acts on mass
     • G is constant through all mediums, for E the force dpeends on the permittivity of the intervening medium