In a (bounded) domain $\Omega \subset \mathbb{R}^n$, if we're studying the Laplace equation or heat equation or such PDE's we can impose the Dirichlet
$u|_{\partial\Omega} \equiv 0$,
Neumann 
$D_{\nu} u|_{\partial\Omega}\equiv 0$
or Robin (for $\alpha \in \mathbb{R}$) 
$(D_{\nu} u + \alpha u)|_{\partial \Omega} \equiv 0$.

I know that, for example for the heat equation, Dirichlet eigenvalues correspond physically to the boundary being in contact with a (large) heat bath at $T=0$. Or, in the Laplace equation, if we're intersted in the modes supported by $\Omega$ (as a drum), Dirichlet boundary conditions can be thought of keeping the boundary from moving.

Neumann boundary conditions, for the heat flow, correspond to a perfectly insulated boundary. For the Laplace equation and drum modes, I think this corresponds to allowing the boundary to flap up and down, but not move otherwise.

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My question is: what sort of physical interpretations are there for the Robin boundary conditions? [Wikipedia](http://en.wikipedia.org/wiki/Robin_boundary_conditions) says that they are related to electromagnetic problems, but gives no details. I'd be happy with answers that are not necessarily physics-related, for example, if there was somewhere that Robin boundary conditions naturally arise in a mathematical context, I'd be interested to know about that as well.