Electrostatics Java Simulation links

http://webphysics.davidson.edu/physletprob/ch9_problems/ch9_1_electrostatics/default.html Physlets

http://webphysics.davidson.edu/Applets/efield4/prb1.html Force vector with 1 unknown charge.
http://webphysics.davidson.edu/Applets/efield4/Forces.html Force vectors with 5 unknown charges.

http://webphysics.davidson.edu/Applets/efield4/field_potentials.html Electric Fields, field lines, and equipotentials. 

http://webphysics.davidson.edu/Applets/efield4/Potential.html 3 different potential fields.  Rank A,B,C
 

http://webphysics.davidson.edu/Applets/efield4/intro.html EField simulator