# Are dc and ac currents produce electric field? [closed]

I have four different situation and i want to learn what kind of field (electric or magnetic) each produces and which produces electomagnetic waves?

1)dc current flow in a conductor

2)ac current flow in a conductor

3)q charge moving v velocity

4)q charge with a accelleration

• What do you want to know about electromagnetic waves? – NeutronStar Nov 3 '13 at 22:19

• Afaik, For 3 the result is not quite the same as a dc current flowing in a conductor, because of the spatial and temporal dependence of the magnetic field. The way to obtain the result is to Lorentz transform the Coulomb field into a frame where $q$ is moving with velocity $v$. I don't think $E$ vanishes in this case, unlike a conductor in which $E$ is zero. – lionelbrits Nov 3 '13 at 22:59