Physics

Problem

A long straight conductor carries a steady current of

10\,\text{A}

and is immersed in a medium of relative permeability

\mu_{r}=4

. Two points

P

and

Q

lie on the same side of the conductor at perpendicular distances

r_{P}=5\,\text{cm}

and

r_{Q}=10\,\text{cm}

respectively. (a) Calculate the magnitude of the magnetic field at

P

. (b) Determine the ratio

\dfrac{B_{P}}{B_{Q}}

and comment briefly on your result.