ABSTRACT
The Dirac delta function δ is defined with respect to variations in space and time, and its main properties are described. The Green’s function G is introduced as the solution D(G) = δ of the equation D(y) = f where D is a differential operator so that the solution of the equation D(y) = f is the convolution integral of G with f, written as (G * f). One first solves D(G) = δ s for each value of s, and since the source is a sum of delta functions, by linear superposition principle, the solution is a summation of the Green function responses over the original function f. Taking a representative example of a conductor under specified conditions, two types of Green’s function, namely the retarded and advanced functions, are found to be satisfying the Green’s function equation. Their physical significance is explained as waves propagating in opposite directions.
