# Is there any example where electric and magnetic fields are not perpendicular?

Perpendicular electric and magnetic field creates light or other electromagnetic waves. Is it a necessary property to have a perpendicular fields? If not what would happen when the fields are not perpendicular?

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A moving electric field, creates the perpendicular magnetic field. –  Optionparty Apr 14 at 19:36
@KaziarafatAhmed: Yes there is! In wave guides there modes of propagation. What we know as transverse electromagnetic field is just the TEM mode of a field. There are also the TE(transverse electric mode) with $B_z\neq 0$ and the TM(transverse Magnetic mode) with $E_Z\neq 0$ where $z$ is the direction of propagation! –  Thanos Apr 18 at 12:33
Just put a charge at rest in a magnetic field. The Coulomb field goes out in all directions, and will cross the magnetic field at every possible angle. Nothing special happens. –  Michael Brown Apr 18 at 12:44
please note that if $\vec{E} \vec{B}$ is not equal to $0$, i.e. fields are not perpendicular, then there always exist a reference frame where $\vec{E}$ is parallel to $\vec{B}$. In particular, this is the case of neutrino field. –  Murod Abdukhakimov Apr 18 at 14:54
@MurodAbdukhakimov: if ... fields are not perpendicular, then there always exist a reference frame where E is parallel to B Not true. The quantity $E\cdot B$ is a relativistic invariant. See en.wikipedia.org/wiki/… –  Ben Crowell Aug 17 at 18:29
Yes there is! In wave guides there modes of propagation. What we know as transverse electromagnetic field is just the $TEM$ mode of a field. There are also the $TE$(transverse electric mode) with $B_z≠0$ and the $TM$(transverse Magnetic mode) with $E_z≠0$ where $z$ is the direction of propagation!