in the electric theory is the kinetic term of the gauge fields $W_\alpha^2$. Its coefficient is $P \log \Lambda$ where $\Lambda$ is a dynamical scale related to the gauge coupling by dimensional transmutation, and $P$ is the coefficient of the one loop beta function (in an $SU(N_c)$ gauge theory with $N_f$ flavors of quarks in the fundamental representation $P=3N_c-N_f$). Even though $W_{\alpha}$ is chiral (annihilated by $\bar D_{\dot
\alpha}$), it is usually not a chiral primary field at the IR fixed point. The reason is that the anomaly equation often relates it to another primary field $\CO$ as $W_\alpha^2=\bar D^2 \CO$. Therefore it is not in the chiral ring. Nevertheless, its coefficient in the electric Lagrangian should be related to its counterpart in the magnetic theory, $\bar P \log \bar \Lambda$ ($\bar P$ is the coefficient of the one loop beta function in the magnetic theory). In our case we will show that the relation has the form

The relation  shows in a quantitative way how one theory becomes stronger as the other becomes weaker. Its consistency with various flows will provide rather stringent quantitative tests of duality.

$\Lambda$ ($\bar\Lambda$) is usually thought of as the scale at which the 