Question

Is the steady electric current the only source of magnetic field? Justify your answer.

Answer 1

Obviously not! I am enumerating few here:

Steady current produces magnetic field.

So does time varying current

Permanent magnetic moment like in permanent magnets

Time varying electric field.

What we can see through these example that nature of electric field and magnetic field is fully symmetric. Changing one changes other automatically. Also, magnetic field in one frame could be combination of both electric and magnetic field.