Module 3 : MAGNETIC FIELD
Lecture 15 : Biot- Savarts' Law

Thus the force between the wires carrying current in the same direction is attractive and is $ \mu_0I_1I_2/2\pi d$per unit length. A generalization of the above is given by the mathematical expression for the force between two arbitrary current loops.

\begin{displaymath}\vec F = \frac{\mu_0}{4\pi}I_1I_2\oint\oint\frac{\vec{dl_2}\times(\vec{dl_1}\times\vec{r_{12}})}{r_{12}^3}\end{displaymath}

where $\vec{r_{12}}$is the position vector of the element $\vec{dl_2}$with respect to $\vec{dl_1}$.

\includegraphics{fig3.28d.eps}

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