Circuit Problem -- With only a battery in the circuit, will current flow?

[Faiq]

Homework Statement

Will current flow in an ideal circuit given that there is only an ideal battery in the circuit?

Homework Equations

V=IR

The Attempt at a Solution

Since there is no resistance through out the circuit no potential is dropped so no current flows

 

[ProfuselyQuarky]

Are you asking if whether a current will flow only if there is a battery?

 

[Faiq]

Yes

 

[ProfuselyQuarky]

Of course. Batteries are the power supply of a circuit. How can there be current flowing through a circuit without any form of power connected to it?

 

[Faiq]

Thanks

 

[ProfuselyQuarky]

Sure . . .

Although I'm curious to know what made you think otherwise?

 

[gneill]

Hold on, do you mean a circuit with a battery only, with its + terminal connected to its - terminal via an ideal wire?

 

[Faiq]

No current is flowing right? I was thinking the same but one guy said otherwise and gave no logic behind his reasoning

 

[Faiq]

And the battery doesn't even have internal resistance

 

[gneill]

Then this is a case of an unrealizable circuit. The ideal battery will want to drive an infinite amount of current through the wire.

You get a similar problem with an ideal current source with open terminals; it will want to create an infinite potential difference across the terminals in order to drive the required current.

In both cases, in the real world, something's got to give. Think: FLASH! BANG! SMOKE!

 

[Faiq]

No I am just asking why would current even flow when there's no potential difference across the circuit

 

[gneill]

No I am just asking why would current even flow when there's no potential difference across the circuit

The ideal battery will attempt to make enough current flow in order to realize the battery's specified potential difference. With no resistance, it cannot accomplish this so the current heads off to infinity.

 

[Faiq]

For current to flow from one point to another point, there should be some potential difference but the whole circuit is on the same potential. Why would current flow then?

 

[ProfuselyQuarky]

do you mean a circuit with a battery only, with its + terminal connected to its - terminal via an ideal wire?

The OP didn't specify any of that

In both cases, in the real world, something's got to give. Think: FLASH! BANG! SMOKE!

This sounds familiar

 

[Faiq]

The ideal battery's positive terminal is connected to its negative terminal by an ideal wire

 

[cnh1995]

The ideal battery's positive terminal is connected to its negative terminal by an ideal wire

That is an unrealizable circuit, as gneill said earlier.

 

[Faiq]

I know but I am just curios to why would current even flow when there's no potential difference across the circuit

 

[cnh1995]

why would current even flow when there's no potential difference across the circuit

Ideal battery tries to maintain a constant potential difference across its terminals. Ideal wires have zero resistance, hence, they try to have 0 potential difference across them. These two opposite behaviors make the circuit unrealizable. One good example gneill gave is of an open circuited current source. Similarly, you can't connect two ideal voltage sources in parallel and two ideal current sources in series. These are unrealizable circuits.

 

[Faiq]

Oh which means that my question is invalid?

 

[cnh1995]

Oh which means that my question is invalid?

The situation in your question is invalid.

 

[Tom.G]

I=V/R
R=0
ERROR, DIVIDE BY ZERO

 

[donpacino]

Note: In a real circuit, that wire would not have 0 resistance.

It would have a very small resistance, so a large amount of current would flow.

Often when thinking about ideal cases, it can help to think what would happen in a slightly less than ideal case