Electric charge and electric force

This lecture is based on HRW, Chap 22:1-6.

Charge comes in two varieties, positive and negative
Charge is quantized, in units of e, the charge on an electron
Charge is conserved
Like charges repel; opposite charges attract
Conductors allow charges to move freely within them; insulators hold charges fixed in place.
Coulomb's Law expresses the force between two charged particles as a function of their charge and separation
Electric forces can be much, much stronger than gravitational ones