NOTE – In a linear medium the electromagnetic energy within a domain V is given by the volume integral
1 2 ∫ V ( E⋅D+H⋅B ) d V MathType@MTEF@5@5@+=feaagCart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbbjxAHXgarqqtubsr4rNCHbGeaGqipG0dh9qqWrVepG0dbbL8F4rqqrVepeea0xe9LqFf0xc9q8qqaqFn0lXdHiVcFbIOFHK8Feea0dXdar=Jb9hs0dXdHuk9fr=xfr=xfrpeWZqaaeqabiGaciGacaqadmaadaqaaqaaaOqaamaalaaabaacbaGaa8xmaaqaaiaa=jdaaaWaa8quaeaadaqadaqaaGqadiaa+veacqGHflY1caGFebGaey4kaSIaa4hsaiabgwSixlaa+jeaaiaawIcacaGLPaaaaSqaaiaabAfaaeqaniabgUIiYdGccaaMc8UaaeizaiaaykW7ieGacaqFwbaaaa@48F2@
where E, D, H and B are the four vector quantities determining the electromagnetic field.