Past exam of the optics and electrodynamics course of the University of Cambridge / 2022 / Section B / 6 / a

Fix coordinates $x^{\mu }=(ct,x,y,z)$ and use the following convention for the contravariant electromagnetic field tensor:For $O^{\prime }$ moving with velocity $+v\hat{\mathbf{x}}$ relative to $O$, the Lorentz transformation hasThe rank-two tensor transformation rule isFor example,Similarly, $F^{\prime 03}=-\gamma (E_z+v{B}_y)/c$ and $F^{\prime 13}=\gamma (B_y+v{E}_z/c^2)$. The $01$ component is unchanged because ${\gamma }^2(1-{\beta }^2)=1$, and the $23$ component is unchanged since neither index lies in the boost plane. Reading off the six field components givesAn alternative overall sign convention for $F^{\mu \nu }$ gives the same physical Lorentz transformation of electromagnetic fields when its identifications with $\mathbf{E}$ and $\mathbf{B}$ are used consistently.