electricity flow

[sammmo]

In an electrical wire is there any electricity actually in the wire if the final circuit is not connected.? IE if you touched a "live" wire you would get a shock because you have completed the circuit through yourself to earth..But before you touch this wire is there any electricity actually in the wire or is it back in the generator?

[R1Geezer]

electricty is the name given to the energy given off by the excitement of electrons in the atoms of the conductor so in that sense it is in the wire but not energised until the curcuit is completed.

[mjd]

Let's assume that you are talking about the UK mains system. The unconnected "live" wire will be at a potential of 230 volts. No current will be flowing because the impedance from the wire to ground is very high.

If you donned a pair of Wellington Boots you could probably grasp the 'live" wire with no ill effects because the impedance from the wire to ground is still very high because of the boots ( this is the principle employed by those people who work on "live" distribution systems.

If you now took the boots and your socks off, sprayed yourself with water then grasped the wire you would get a shock because the impedance to ground is now low enough to allow a large current to flow, and this current flowing through your body would probably stop your heart.

[mjd]

By the way I don't recommend that you do put on a pair of rubber boots & start touching "live" wires.

[mibn2cweus]

The human body being a relatively good conductor has a capacity to absorb retain and release a charge. The amount of charge it will absorb depends on the individuals size, the magnitude of the applied voltage, their proximity to other conductive bodies (which would increase their capacitance) and their isolation from other charge carriers that would allow the charge to pass through or bleed out of their body.

An alternating voltage (such as mains voltage) having a constantly varying potential will force a charge into and out of the human body in proportion to the applied voltages magnitude and frequency of alternation. The alternating difference in voltage potential between the conductor and the attached body is what produces the current flow.

Depending again on the magnitude of the voltage at the time one releases the voltage conductor one could potentially carry the accumulated charge over to another conductive body (such as a doorknob) and release part of the charge accumulated until (almost instantly) the difference in charge between them is equalized.

You may want to Google human capacitance for more information relating to this subject

[sammmo]

Thanks for that but what i need to know is ..Whether or not there is any electricity actually in the wire or is it in the genorator and as the circuit is made it is only then that the wire has electricity runing through it.. or is there electricity in the wire all the time?

[ChuckFickens]

There is electricity (well electrons) in the wire all the time but it won't do anything until you put more electricity into one end of the wire to cause a current to flow.

Much like a hose pipe can be full of water but it won't start coming out the end until you turn on a tap to put more water in the other end.

[mibn2cweus]

A wire being a conductive body will absorb enough current to provide the equivalent counter emf, depending on its capacitance including environmental effects determining its capacitance.

If the applied voltage is alternating (changing over time) the required charging current will flow into and/or out of the wire.

[Teddio]

The copper wire is saturated with electrons. To get the electrons to flow you need a potential difference. This potential difference is measured in Volts and is usually provided by a generator or a battery.
Electric current is the flow of electric charge and is measured in Amperes. One Coulomb of electric charge flowing per second is one Ampere.
Potential Difference is the work done (or energy transferred) per Coulomb of charge passed.

[chakka35]

Teddio, first part fine, but PD is not a measure of energy but, as it says, a difference of the potential between two points, measured in volts.
Thus if point A is at plus 2 volts (with respect to earth, say) and point B is at 6 volts the PD between them is 4 volts.