Figure $29-35 a$ shows an element of length $d s=1.00 \mu \mathrm{m}$ in a
very long straight wire carrying
current. The current in that element sets up a differential magnetic field d\vec at points in the surrounding space. Figure $29-35 b$
gives the magnitude $d B$ of the field
for points 2.5 $\mathrm{cm}$ from the element, as a function of angle $\theta$ between the wire and a straight line to the
point. The vertical scale is set by $d B_{s}=60.0$ pT. What is the magnitude of the magnetic field set up by the entire wire at perpendicular
distance 2.5 $\mathrm{cm}$ from the wire?