enter image description here Let's say I have a 5V battery connected in the manner shown in the diagram. I've tried this setup with all sorts of things like pouring brine(salt water) into the soil to decrease its resistance so that the current flows through it, (I mean electrons flow from the ground and neutralize the positive charge as happens in the case of charging by induction when the second sphere is connected to ground) and the battery dies but nothing of that sort actually happens. I understand how charging metallic spheres by induction works(in the case of inducing a negative charge on the second sphere when it's connected to the ground) but i want to know -

Why don't electrons flow from the ground to the positive terminal of the battery and neutralize it even though the positive terminal is at a higher potential than the ground by 5 volts and the ground is universally at a potential of 0V ?

And secondly,

is my current understanding of potentials (as I've used in the figure) correct or am I missing something?

Any help is greatly appreciated.

  • $\begingroup$ Where did you get the a priori knowledge that the positive terminal of the battery is at a higher potential than ground in your first bolded question? $\endgroup$ – The Photon Dec 28 '18 at 16:59
  • $\begingroup$ I've assumed that both the negative terminal and the ground are at a potential of 0 volts. Isn't this how ground works? Correct me. $\endgroup$ – user8718165 Dec 28 '18 at 17:01
  • $\begingroup$ It isn't how ground works. If the negative terminal isn't connected to earth ground, there's no reason to think it should be at the same potential as earth ground. $\endgroup$ – The Photon Dec 28 '18 at 17:05
  • $\begingroup$ Aren't we always told to use the negative terminal as a reference which equals 0 volts while solving circuits? $\endgroup$ – user8718165 Dec 28 '18 at 17:09
  • $\begingroup$ Yes, if the circuit is isolated from earth, you can designate whichever node of the circuit you want as "ground" and solve all your voltages relative to that. Very often the most negative node in the circuit is chosen as ground. And very often that is the negative terminal of a battery. But that doesn't mean the negative terminal of the battery has a magical way to keep itself at the same potential as earth ground. Consider that there are battery-powered circuits in airplanes, on the moon, and on space probes far from any planet at all. $\endgroup$ – The Photon Dec 28 '18 at 17:12

Your drawing shows some wrong information.

If this configuration is allowed to settle for a millisecond or so, the positive terminal of the battery will be at 0 V, and the negative terminal of the battery will be at -5 V.

Before you connect the positive terminal to earth, assuming it wasn't connected to anything else, there's no way to know the potential difference between the battery and the earth. The negative terminal could be at 0 V, 1000 V, -1000 V, or anything in between, due to stray charge (static electricity) on the battery. Whatever potential the negative terminal has, the positive terminal will be 5 V higher.

  • $\begingroup$ How do the potentials at the terminals change after a millisecond? I've isolated the terminals. $\endgroup$ – user8718165 Dec 28 '18 at 17:29
  • 1
    $\begingroup$ A millisecond may be an overestimate. I'm just saying that there will be a brief instant when you first connect the battery to ground when current flows through the wire to equalize the potential at the two ends of the wire. This is the current that neutralizes any static charge that built up on the battery before it was connected to earth. $\endgroup$ – The Photon Dec 28 '18 at 17:34
  • $\begingroup$ Thanks now i get that my figure is incorrect. But why does't charge flow between a battery and earth while induction charged spheres easily exchange charges with the ground? $\endgroup$ – user8718165 Dec 28 '18 at 18:43
  • $\begingroup$ @user8718165, if you brought another charged object close to the battery (with one terminal connected to ground), it would momentarily cause a current to flow between the battery and ground, just like an induction charged sphere. To see why this is a complete circuit (in reference to the link) you should include the capacitance between the earth and the other object, and between the other object and the battery, in your circuit model. $\endgroup$ – The Photon Dec 28 '18 at 18:56
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    $\begingroup$ @user8718165, yes that's correct. In this case there is no net charge on the battery as a whole, so there's no transfer to ground when it's connected. It would be different if initially there were 1,000,000 electron charges on the positive terminal and 1,000,010 electron charges on the negative terminal, for example. $\endgroup$ – The Photon Dec 28 '18 at 19:17

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