Charge accumulated at two ends of resistor/inductor? In a simple circuit are there any charges accumulated at two ends of resistor? There is an conservative and thus electrostatic electric field and potential difference across the resistor. It seems it is only possible if positive and negative charges are accumulated at two ends to provide the electric field. Can these kind of extra charges be detected in a real resistor? How?
Same questions for inductor in the case of changing current in inductors. Thank you. 
 A: Microscopically, in a resistor electrons are scattered by lattice impurities and defects (e.g. surfaces), other electrons and phonons.
An approximate description of the process: In the classical approximation of the Drude model the scattering processes are reduced to a scattering time $\tau$, in between the scattering processes the electrons move balistically (that is freely accelerated by the electrical field).
So the actual process is highly statistical an non-trivial and the voltage drop
has to be accounted to the electrical field losing energy due to the acceleration of the electrons and thus being reduced. (Actually the flow of energy of the electromagnetic field (Ponyting vector) around a resistor is inwards, when you consider the whole setup it will flow out of the source (where electrical and magnetic fields will have reversed directions compared to each other as the current has the same direction everywhere, but the electrical field direction is against the current in the source) into the wires.) So you can see, the situation is stationary but not static, there always is an energy flow going on. The dynamical equilibrium between this energy inflow and the energy losses of the electrons to the resistor cause the electric field to drop without charges accumulating. (And on the microscopic scale the process is not even stationary!)

In the case of the inductor the answer is simple and a clear no. The relevant Maxwell equations is:
$$ \nabla \times \vec E = -\frac{1}{c^2} \partial_t \vec B $$
This says, there is another way of generating electrical fields than accumulating charges. When the current through the wire changes the
generated magnetic field changes, thus inducing an electrical field with closed field lines (that is, without sources and sinks).
So actually the field involved here is not even conservative (just it's projection to the effectively one dimensional wire is).
So in a way the description of these processes by an electrical potential is cheating and only possible because the wires are effectively one dimensional (and roughly every one dimensional function has an antiderivative). In the entire 3d-space an electrical potential alone cannot account for the observed fields (one also will have to consider the vector potential there).
