Question

explain the point that the magnitude of the magnetic field produced by a straight current carrying wire at a point is inversely proportional to the distance of this point from the wire

Answer 1

Dear Student ,
Look according to the Biot-Savart's law magnetic field produced by a straight current carrying conductor is directly proportional to the current flowing through the wire and length element($\delta l$) of the wire and inversely proportional to the distance(r)between the point from the wire .
Therefore according to the Biot-savart's Law , magnetic field is ,
$\overrightarrow{B}=\frac{{\mu }_0}{4\pi }\sum _{}^{}\frac{I\left(\delta \overrightarrow{l}\times \hat{r}\right)}{r^2}$
Regards