cation.</p>
<p>Used to define an external electrical field at a point independent of the vertex charges.
A vertex L is acted upon by a force in the X direction of proportional to
<code>electricalFieldX(L.center.x, L.center.y) * electricalCharge(L)</code>.
Please read the Introduction page on <a href="../../intro/extensions.html">Extensions</a> for how to override methods and how to call this base method.</p>
</div><div class="tsd-parameters"><h4 class="tsd-parameters-title">Parameters</h4><ul class="tsd-par