This is what I always thought: Why do we always need resistors in our circuits? What if we use one battery and just a piece of cable without a resistor? Why do electrons in a battery not "go out" in these conditions, and why doesn't our circuit become complete?
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5Please clarify what you're asking, and do bother to include some schematics. – Dzarda May 28 '14 at 19:02
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The question is based on a couple of false premises.
Resistors are not always needed in every circuit. A simple example is a coin cell operating an LED. Or consider a lamp powered by household mains.
In both cases you could consider the load (the LED or lamp) a type of resistor (i.e., it resists the flow of electrons), but it is doing useful work (producing light).
Resistors, in general, are meant to limit current flow, so that other components are not damaged. However, they aren't required for every circuit.
The word circuit is defined as "a path or trip around something." If you don't connect your wire to the battery in such a way that you've created a loop, it isn't, by definition, a circuit. If you connect a wire to only one side of a battery (with or without a resistor), you haven't formed a complete circuit, and no current will flow. In order for electrons to "go out" of the battery, they must have a return path. This is because a battery is actually a sort of pump for charge (but not a charge pump, per @Phil's comment). Electrons must flow from one terminal to the other in a complete circuit.
You may find it helpful to read about basic electric circuits at AllAboutCircuits.com.
