Electromagnetism 2004 Fall Zhang Yang Dept. Astron. appl. Phys Reference K Electromagnetism, principles and application》 by p.lorrain d corson
Electromagnetism 2004 Fall Zhang Yang Dept. Astron. & Appl. Phys Reference: 《 Electromagnetism, principles and application》, by P.Lorrain & D.Corson
Chapter 2 Fields of Stationary Electric Charges Coulomb' s Law Electric Field intensity E Superposition and EXtented Charge Distribution Electric Potential Electric dipole
Chapter 2 Fields of Stationary Electric Charges ◼ Coulomb’s Law ◼ Electric Field Intensity E ◼ Superposition and Extented Charge Distribution ◼ Electric Potential ◼ Electric Dipole
2.1 Coulomb,s law Given two stationary point charges Qa and qb, it is experimentally found that the force exerted by la on 1 OO r 丌∈0 where ri is a unit vector pointing in the direction from Qa to Qb, and the permittivity of free space(vacuum) 0=8.854187817×10-12 arad/meter nterpretation
Figure 2-1 Charges Q, and @, separated by a distance r. The force exerted on Q, by 2, is F and is in the direction of r, along the line joining the two charges
Explanation (1) the force acts along the line joining the two charges, (in the direction r1) (2)the force is o the product QaQb, so the force is repulsive if @a&@b are of the same sign attractive if @a&@b are of the different sign (3 the force x r, important.(what if not Unit: (in SI Unit System) ab- newton; @a Qb-coulomb; r--meter