A very long straight conductor carries a steady current of in air

PHYSICS · Subjective · AP · Physics C: Electricity and Magnetism · Magnetic Fields and Electromagnetism · Magnetic Fields and Electromagnetism

Problem

A very long straight conductor carries a steady current of

25\,\text{A}

in air. (i) Calculate the magnitude of the magnetic field at a point

4.0\,\text{cm}

away from the conductor. (ii) The same conductor is now immersed completely in a liquid whose relative permeability is

4.0

. Find the magnetic field at the same point

4.0\,\text{cm}

from the wire. (iii) By what numerical factor has the field changed when the wire is moved from air to the liquid?