Case : Read the passage and answer the question(s).

The basic equation governing the magnetic field due to a current distribution is the Biot-Savart Law. Finding the magnetic field resulting from a current distribution involves a vector product and becomes an inherent calculus problem when the distance from a current to the field point is continuously changing.

According to this law, the magnetic field at a point due to a current element of length dl carrying a current I, at a distance r from the element is

dB = (μ_o/4π) I (dl x r)/r³.

Biot-Savart Law has certain similarities as well as difference with Coulomb's Law for electrostatic field as there is an angle dependence in Biot-Savart Law which is not present in electrostatics.

dB = (μ_o/4π) I (dl x r)/r³.

Biot-Savart law has certain similarities as well as difference with Coulomb's law for electrostatic field as there is an angle dependence in Biot-Savart law which is not present in electrostatics.

What can be said about the magnetic field due to a current in a straight wire segment of length L at a point on its perpendicular bisector at a distance r (r>> L) 

decreases as 1/r²

Using Biot-Savart law and using r>>L,

B = μ_oI/4πr².