Retarded Potentials and Review of Potentials for the Static Cases

The basic equation is 1B.1 ∇ × E = 0 . https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315272351/41040b79-9956-496a-ac34-683fa4364729/content/eqn1b_1.jpg"/> It is known that the curl of the gradient of any scalar is zero, that is, 1B.2 ∇ × gradient of any scalar ≡ 0. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315272351/41040b79-9956-496a-ac34-683fa4364729/content/eqn1b_2.jpg"/>