What is Helmholtz theorem?? Use it to show only transverse component of current density exist in wave equation??

Yuvrajj Vatt asked

Please refer to https://en.wikipedia.org/wiki/Helmholtz_theorem_(classical_mechanics)

http://farside.ph.utexas.edu/teaching/em/lectures/node37.html

http://www2.ph.ed.ac.uk/~rhorsley/SI09-10_t+f/lec19.pdf

http://mathworld.wolfram.com/HelmholtzsTheorem.html