If several point charges Qi are inside th e fields is E=∑E2 The flux of e thru a small element of area da is E·da=∑E;da Integrating over S yields Q2;1 /sE.da=∑ ∑Q ∈ For a general distribution of charge inside s Q=/p(r')di so we have E da=o/p(r) The gauss law in integral form