# Flow of current in open circuit

If we place a bunch of positively charged particles on one side of a conducting wire and a bunch of negatively charged particles on its other side, the situation will be analogous to a battery. Will then current flow in the open conductor for a small amount of time until the whole positively charged particle gets neutralized? OK, current flow is possible. But can we create a steady current in this way?

• Like the capacitor which stores electric field then discharge until the charges balance on both sides. – user6760 Nov 12 '16 at 7:52
• Here +ve and -ve particles on either side does the job of a battery for a limited amount of time. So will current flow for a small amount of time in the conducting wire?? – user130324 Nov 12 '16 at 7:58
• The answer is yes. – Steeven Nov 12 '16 at 17:51

A charged conductor has a potential $V$ that depends on the amount of charge carried and on the geometry of the conductor. In general, when two conductors with different potentials are connected with a conducting wire, a transient current passes from the body with higher potential to that with lower potential. The current persists till the potential difference drops to zero, and this usually takes a very short duration of time.

If the two conductors initially have equal and opposite charges, zero potential difference is obtained when both conductors are neutralized.

Edit:

Yes it is practically possible: two conductors having the same charge with an opposite sign actually form a capacitor by definition, and when we introduce a resistance into the circuit, the schematic representation becomes: Our job is to find suitable values for $C$ and $R$ to extend the discharge duration as long as possible.

We can apply Kirchoff's voltage law and solve for the current as a function of time, we get:$$I=\frac{V}{R} e^{-\frac{t}{R.C}}$$ Where $V$ is the initial voltage. Current decays to practically zero at $t=5R.C$, where $t$ is in seconds, $R$ in ohms, and $C$ in Farads. So, a $1 M\Omega$ resistor and a few $\mu F$ capacitor can create a current that persists for quite a few seconds.

• "The current persists till the potential difference drops to zero, and this usually takes a very short duration of time." Approximately how much time does it take for the potential difference to reach zero? Also by using what type of conductors and conducting wire can we increase the time to the most possible extent? – user130324 Nov 12 '16 at 8:31
• @stack exchange Its time duration depends on initial conditions (total charge, voltage, resistance of the wire ), but it is usually very short (micro seconds). You can extend it by using a large charge and a M$\Omega$ resistor. – Tofi Nov 12 '16 at 10:57
• Is it practically possible to build such conductors where the time duration is a few sec – user130324 Nov 12 '16 at 14:47
• @stackexchange i've edited the answer to cover that. – Tofi Nov 12 '16 at 16:18
• One more question "can we create steady current in this way?" – user130324 Nov 13 '16 at 14:52