Q&A: Black Holes
A magnetic field is produced by a circulating charge, so if
the net charge is zero a black hole should not have any
magnetic field, so how could a a black hole have a magnetic
field to produce the jets seen rushing away from them?
Although it is possible though not believed likely, that a
black hole could be charged, they are not expected to have a
magnetic field. The magnetic fields around a black holes that
are thought to produce the spectacular jets of high-energy
particles rushing away from black holes come from the disk of
hot gas around the black hole, not the black hole itself.