# Short ckt increase?

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#### Wond3rboy

##### Member
Hi i know some might find this question useless(its another thing lke the capacitor response to a square wave i asked before) but here goes.

How actually does current increase when a battery is short circuited?I mean wrt to time not voltage.

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#### dknguyen

##### Well-Known Member
The same as a current increases through an inductor with a fixed voltage- it ramps up linearily. Except inductance of a wire is usually very small so the current ramps up very quickly. It does so until current is limited by the resistance of the wire.

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##### Member
About your point 'the current is limited by the wire', if current was 'limited' by the wire contextually speaking that way the wires wouldnt burn up? I know this is not true just asking cause as far as i know the battery is the one controlling the current by supplying the max current it can to try to maintain voltage.

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Thanks dknguyen.

#### tunedwolf

##### Well-Known Member
The current being supplied by the battery is limited by the internal resistance of the battery itself. If this is low, the current flowing in a short circuit or near short circuit will be on the high side.

The wire will, in essence, act as a resistor, albeit a low value one, and not as a true short, as will that of the internal resistance of the battery. It is this that will define the actual speed of current increase.

Obviously, the lower the resistance of the circuit, the higher the current will be allowed to flow through that circuit and the lower the time taken will be to get it there.
Also remember that the current will be the same in all parts of the circuit, so it is not only the wire being subjected to the high current, but in the battery also.

rgds

#### colin55

##### Well-Known Member
Obviously, the lower the resistance of the circuit, the higher the current will be allowed to flow through that circuit and the lower the time taken will be to get it there.

should be: "same time"

The high current-flow is instantaneous. It just takes time for the wire to heat-up and this makes it appear that the current-flow increases or decreases. Current-flow generally decreases with time due to the cell polarising as the bubbles of gas reduce the effective area of the plates.

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