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What is current of electric circuit which has only one component a battery (or cell)? Explain why.

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closed as not a real question by Emilio Pisanty, Manishearth Dec 18 '12 at 17:59

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I can't understand what you mean by "handle"... Do you mean, "Take by hands" ? –  Waffle's Crazy Peanut Nov 18 '12 at 18:53
    
I fixed question a bit. I meant analyze. –  laovultai Nov 18 '12 at 18:55
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I think it's still unclear. The rate of flow of charges is called current. What do you require? Minding you of Wiki for these questions..! –  Waffle's Crazy Peanut Nov 18 '12 at 19:00
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2 Answers 2

up vote 2 down vote accepted

Initially it is the voltage of the battery divided by it's internal resistance (plus that of the conductor completing the circuit across the battery terminals). Because of Ohms Law

See A-level Physics (Advancing Physics)/Internal Resistance/Worked Solutions answer 1.

The Internal resistance of a battery depends on its chemistry, construction, current, temperature and other factors. As the energy stored in the battery is converted to heat, the internal resistance will change. Since batteries are not designed to be in a circuit with no other components, it is very likely the battery will quickly fail, for example the electrolyte may boil.

It is this type of experiment that helps to keep our gene-pool healthy.

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So in this case, because cell creates voltage $U \neq 0$, current $I$ should be $\infty$, if the resistance R of the circuit is 0. Ok? –  laovultai Nov 18 '12 at 20:41
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Resistance of a superconducting circuit can be roughly zero. However, I know of no battery that can produce infinite current (it would produce an absurd magnetic field, among other problems), so I think the proper conclusion is that the battery cannot supply enough current to produce a nonzero voltage across a circuit with no resistance. –  Andrew Nov 19 '12 at 4:28
    
@alvoutila: As you know, commonplace batteries have internal resistance. The metals most often used to create circuits also have resistance in the range of temperatures that most batteries are designed to operate. If your question is about special temperatures, special batteries or other special circumstances it may be useful to revise your question to say so. –  RedGrittyBrick Nov 19 '12 at 10:10
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You don't have a one component system because batteries are not ideal. You can replace the battery with a (theoretical) "ideal" voltage source or a (real) super conducting capacitor.

If you use an "ideal" voltage source, the current will increase rapidly (not instantly because the wire has an inductance). It will continue to increase rapidly forever (well until the wire blows). Even theoretically, the current can't actually be "infinite" because electrons have a finite mass (E potential -> force on the charge -> a=f/m).

It's interesting to replace your battery with a perfect, superconducting capacitor because this is "doable" in a lab. Let's assume there are no losses (no parasitic losses, no restive losses). The wire "shorting" the capacitor has a finite, non zero, inductance. So you end up with an oscillator circuit, with a very high Q.

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