Question

If the magnetic field is measured to have a strength of 242.25μT directed at an angle of 325°, what is the location of this measurement?

A wire carrying 969mA is travelling upwards along the Z axis through four different materials, one in each quadrant. The first quadrant is composed of cobalt; the second quadrant has iron, the third quadrant is made of nickel, and the 4th quadrant is air.

Answer 1

As the measurement of magnetic field were taken along an angle of `325^@`, the point of observation lies in the fourth quadrant.
It is given that this quadrant is composed of air. We know that the strength of the magnetic field `vecB` depends on the current `I` in the wire and the distance `r` from the wire. The expression is
`|vecB|=(mu_@I)/(2pir)`
where `mu_@` is the magnetic permeability of free space and is `4pixx10^-7TmA^-1`.

Inserting given values
`242.25xx10^-6=(4pixx10^-7xx969xx10^-3)/(2pir)`
`=>r=(4pixx10^-7xx969xx10^-3)/(2pixx242.25xx10^-6)`
`=>r=8xx10^-4m`