Physics education research, electronic materials, and the musings of Christopher Moore, Ph.D.

Need to find information about proving that Coulomb forces in vacuum and in dielectric differ in epsilon. (http://www.fmclass.ru/inc/pictures/a...755f42be7b.png and
http://www.fmclass.ru/inc/pictures/5...83f1b6b05f.png)
Or to prove simplier variant - that this forces differ in epsilon on interaction in capacitor whith dielectric between plates and whithout it.