Electromagnetic jump conditions across a normally moving plane
= Electromagnetic jump conditions across a normally moving plane
If a plane is stationary in one frame and an observer moves normally to it with velocity $\mathbf v$, then
$$
[B'_n]=0,
\qquad
[\mathbf E'_t]=\mathbf v\mathbin\times[\mathbf B'_t].
$$
The second relation accounts for the magnetic-field discontinuity moving through the observer's frame.