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.

Two long straight wires are set parallel to each other. Each carries a current I in the same direction and the separation between them is 2r. The intensity of the magnetic field midway between them is?  

Zero

B₁= -μ_oi/2πx and  B₂ = μ_oi/2π(R-x) where x = 2r/2 and R = 2r

Net B = B₁+ B₂

hence, Net B = 0