- #1
EricTheWizard
- 14
- 0
Hi, I've been trying to derive the electromagnetic stress tensor on my own, and I've run into a bit of a problem. I have a cross product of a curl [tex](\vec{E}\times(\nabla\times\vec{E}))[/tex] that I need to expand, and the typical [tex]\vec{A}\times(\vec{B}\times\vec{C})=\vec{B}(\vec{A}\cdot\vec{C})-\vec{C}(\vec{A}\cdot\vec{B})[/tex] isn't cutting it, as the book says this special case is [tex]\vec{E}\times(\nabla\times\vec{E})=\frac{1}{2}\nabla(E^2)-(\vec{E}\cdot\nabla)\vec{E}[/tex]. I've been trying to work this out myself on paper, but to no avail. Can anyone point me to a proof for this or show me how? Much appreciated.