Electric field from a battery...

[aryajur]

If we take a normal battery, so it has a positive terminal and negative terminal. And we have a potential difference across it. So that means there is an electric field. So that means a positive charge will be repelled by the positive terminal of the battery? And the negative charge will be repelled by the negative terminal of the battery? Seems like this should happen, but is there a way to confirm this?

 

[ehsanelahimirza]

hi

u can check by connecting another battery very easily

it will burnout wire or at least very strong heating will b there

 

[hnejati]

till the time that you connect it in the closed circuit there is no transfer of charge be cause a battery is a place where stored charges remain, they are separated in 2 groups +,_ and it is in equilibrium but when you connect it in an external circuit these charges can move and so on
ther is nothing in the name of + or _ terminal
to understand that let's think about an electrolytic cell with 2 electrodes and electrolyte you can not say which terminal is + _ till some charges receive to equillibrium inside that cell

 

[aryajur]

Thinking about an electrolytic cell in an open circuit the chemical reactions will start producing electrons and ions as soon as we pour in the chemicals and the electrodes will should become charged and then that charged electrode will then stop further reaction from occuring and then the electrolytic cell will be in equilibrium. Having a potential across the electrodes.
So now when an external circuit is connected charge starts moving to neutralize each electrode and thus the electrode charge decreases, thereby the chemical reaction again resumes and replenishes the charge.
So the electrodes should be charged, to positive and negative, and thus should generate electric fields, but the electric field around a normal cell would be hard to detect since it would just be present between the electrodes, any place outside the electrodes it would cancel off from each electrode.

 

[cherrytart]

Electrons flow from Positive terminal to the Negative terminal INSIDE the battery and from the Negative terminal to the Positive terminal OUTSIDE the battery. This is because work is done internally to move the electrons against the electric potential.

 

[aryajur]

Electrons flow from Positive terminal to the Negative terminal INSIDE the battery and from the Negative terminal to the Positive terminal OUTSIDE the battery. This is because work is done internally to move the electrons against the electric potential.

Thats true but the question is about the Electric Field detection from a battery.

 

[Ahmed Ragab]

Well this discussion seems quite nice.
I'm not sure how to check this electric field, mainly because all what we deal with in real life is time varying fields, which are much easier in checking (through induced magnetic field and induced currents)

Maybe we can try to charge any materials (the old wool and hair comb game) and try these charged bodies with the terminals of a car battery (can give high currents therefore must be containing high density of charges) and see the effect of the fields if any exist.

Just a thought, I'll try to do it sometime and inform you of any results.

 

[ehsanelahimirza]

Well this discussion seems quite nice.
I'm not sure how to check this electric field, mainly because all what we deal with in real life is time varying fields, which are much easier in checking (through induced magnetic field and induced currents)

quote]

hi

its very good idea but i have experinced this charge effect many times
when i use to change my shirt. it gave me a very good current jerk

 

[advaita]

Hi aryajur

Just curious why you want to do this?

Anyway, are you referring to the point that since the anode and cathode are pretty much parallel in normal batteries (using concentric shells) so there will only be slight fringe electric field outside the battery and rest inside the battery. So you can't feel it using conventional methods?

Just thinking - can't one shake the battery fast enough to observe a magnetic field and conclude that there must be some dipoles inside the battery causing this magnetic field.

 

[jiripolivka]

Yes, a battery generates an electrostatic field outside, between its terminals and connected structures. Detecting such field is tricky as the gradient is low, compared e.g. to a high-voltage electrostatic generators (Wimshurst's machine, glass rod charged by leather stroke, etc.) You can visualize it under a microscope: a powder of non-conductive particles in oil will exhibit a visible movement when you insert electrodes in it, over a distance of < 1 mm.
Electrostatic voltmeters using a chopper can detect gradients of < 1V/meter.
Another proof you can obtain if you connect e.g. a 10-100 such batteries in series: with such gradient you can see an electrometer move.