Module 3 : MAGNETIC FIELD
Lecture 19 : Mutual Inductance

\includegraphics{fig3.50b.eps}


which gives  \begin{displaymath}M_{21} = \frac{\mu_0\pi}{2}\frac{R_1^2R_2^2}{(R_1^2+d^2)^{3/2}}\end{displaymath}

The expression above is obviously not symmetrical between the loops. This is because of our assumption of uniform field over $C_2$. The approximation will be legitimate if the dimensions of $C_2$is negligibly small, i.e. if $C_2$is taken to be a dipole, $d>>R_1$, so that from $C_1$, the other loop looks like a point. In such a case,

\begin{displaymath}M_{21} = \frac{\mu_0\pi}{2d^3}R_1^2R_2^2\end{displaymath}

In the next example we assume that the current is changing in the dipolar loop and determine the emf generated in the larger loop.

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