- #1
Psi-String
- 79
- 0
Maxwell stress tensor:
[tex] T_{ij} = \epsilon_0 \left( E_i E_j - \frac{1}{2} \delta_{ij} E^2 \right) + \frac{1}{\mu_0} \left( B_i B_j - \frac{1}{2} \delta_{ij} E^2 \right)[/tex]
We can interpret T as the force per unit area acting on the surface. But what surprises me is, [tex]T_{ij} = T_{ji}[/tex], i.e. the electromagnetic force (per unit area) in the ith direction acting on an element of surface oriented in the jth direction is equal to the electromagnetic force (per unit area) in the jth direction acting on an element of surface oriented in the ith direction !
It seems like a result of mathematical derivation, but could we get the same result by simple physical interpretation without math??
Anyone have idea?? Thanks a lot!
[tex] T_{ij} = \epsilon_0 \left( E_i E_j - \frac{1}{2} \delta_{ij} E^2 \right) + \frac{1}{\mu_0} \left( B_i B_j - \frac{1}{2} \delta_{ij} E^2 \right)[/tex]
We can interpret T as the force per unit area acting on the surface. But what surprises me is, [tex]T_{ij} = T_{ji}[/tex], i.e. the electromagnetic force (per unit area) in the ith direction acting on an element of surface oriented in the jth direction is equal to the electromagnetic force (per unit area) in the jth direction acting on an element of surface oriented in the ith direction !
It seems like a result of mathematical derivation, but could we get the same result by simple physical interpretation without math??
Anyone have idea?? Thanks a lot!