# Jefimenko's equations

## Answers and Replies

ShayanJ
Gold Member
That means a volume element. In Cartesian coordinates its $dx' \ dy' \ dz'$, in spherical coordinates $r'^2 \ \sin\theta' \ dr' \ d\varphi \ d\theta$ and in cylindrical coordinates $\rho \ d\rho' \ d\varphi' \ dz'$.