Why doesn't Bernoulli's Principle apply to Current and Resistors in a circuit? Bernoulli's principle makes sense when you apply it to fluids. If you decrease the diameter of a pipe then the velocity of the fluid increases because it needs to keep the same rate of fluid moving through the pipe. 
So my question is:
If Voltage == Diameter of the pipe
and
Current == Rate of which the fluid is moving
Why do resistors work?
Shouldn't the resistor only actually work within itself but then return the current to it's actual rate once you have passed it?
Or have I taken the analogy of wires being like pipes of water to far?
 A: Well AMR, your analogy is wrong on two levels.   First of all Bernoulli's principal is different from what your example indicates, that you think it is.
And secondly, your  model with Voltage equated to diameter of the pipe is not a good one either.
BUT, all is not lost; comparing water flowing in a pipe with electric current flowing in a circuit, is not a bad analogy; BUT ! here's how you need to adjust your model.
The Voltage in your circuit, would translate to the water pressure being applied to the pipe.
And secondly, your pipe diameter, would relate in some fashion to the resistance in the circuit.
A smaller diameter pipe, would be equivalent to a higher resistance, since that's what would constrict the current or water flow.
So if you think of Voltage or water pressure, as being the driving "force", and pipe diameter, or circuit resistance as being the impediment to flow, then you can see how the water or electric current flow would vary with those variables.
A: Yes, you've taken the analogy too far: electrons don't actually move through the wire in the way that fluids flow through a pipe. Hence, there is no reason why an analog of Bernoulli's principle should apply.
A: Yes, the analogy is not perfect as voltage can be thought of only as the pressure gradient across the pipe. This analogy will work quite well. For example, as the voltage increases across a wire, the current flow will increase for a given resistance. Similarly, as the pressure gradient increases across the pipe, the flux or rate of fluid transfer will also increase provided other things are held constant. 
A: So you can apply Bernoulli's theorem but not according to your analogy take velocity of fluid as electric field at that position now electric flux is conserved since no charge enclosed in it so as diameter is large electric field will be less.
A: True but in my experience traffic is usually jammed up before going through a tunnel but when you get to the other side the traffic magically disappears....same amount of cars same amount of roads space. 
