<p>Think of the electric current as a fluid, and a battery or some other source of current as a pump. Change the earth for the ocean.</p>
<p>I don't know about the negatively charged earth's surface, but those -500,000 coulombs are an absolute measure of charge. That charge is distributed over some surface, and the earth's surface is pretty big.</p>

CC BY-SA 4.0
2021-02-21T19:39:40.377Z
2021-02-21T19:39:40.377Z
rasmodius
<p>Yes, <a href="https://hypertextbook.com/facts/1998/TreshaEdwards.shtml" rel="nofollow noreferrer">the earth has a field strength.</a></p>
<p>That page quotes field strength numbers of 300V/m or 150 newtons per coulomb. I've not bothered to do the equation for -0.5MC charge across the surface of the earth, but I expect it would line up with that.</p>
<p>The next question is why we don't notice this. I believe it's dominated by other effects; regular tribocharging can build up multiple-kilovolt charges on an ordinary human, and they don't notice until they touch a grounded object and get a small zap.</p>

CC BY-SA 4.0
2021-02-20T14:40:21.747Z
2021-02-20T14:40:21.747Z
pjc50
<p>A lot of misinformation about earth and it being a sink is spread everywhere, including what I was taught in school, I hope you well-informed folk can help me out.</p>
<p>A <em>sort of</em> side-note, if anyone has a book recommendation explaining these kinds of concepts and everything related to them, please do let me know. It seems as if most books on electrodynamics don't really examine these assumptions we usually make. Examples: why earth is a 'sink' for electrons?; how, when grounding houses -- does a ground connection act as a wire which connects back to the same circuit, even when it's a <a href="https://upload.wikimedia.org/wikipedia/commons/7/7d/HomeEarthRodAustralia1.jpg" rel="nofollow noreferrer">single wire</a> (taken from <a href="https://en.wikipedia.org/wiki/Ground_(electricity)" rel="nofollow noreferrer">Ground</a> wikipedia page) connected to ground?
And the list goes on.</p>
<p>To quote my last question, I found it here: <a href="https://electronics.stackexchange.com/a/148684">https://electronics.stackexchange.com/a/148684</a><br />
Quote:
&quot;Current never ever ever ever flows <em>to</em> earth. It only ever flows <em>through</em> earth. Earth is just another wire - albeit a planet sized one. Electrons have to flow from one side of the power source back to the other. They can never flow out and never return.&quot; – Majenko</p>
<p><strong>Moving on, the original question</strong>:
Why aren't objects close to the surface polarized?<br />
We know that by static inductance, when you rub two of the right materials together, one becomes negatively charged, and the other positively charged. Let's take one and get a neutrally charged material next to it, bringing it closer, we can see that it becomes polarized.</p>
<p>I've read that earth's surface is negatively charged, -500,000 coulombs, to be sure. So bringing a neutrally charged object close to it would make it polarized, is what I think is logical.</p>
<p>So why is my conclusion wrong, if it is wrong (doesn't seem right)? And why is it that earth is charged negatively?</p>

<electromagnetism>
If the earth's surface is negatively charged, why aren't objects close to the surface polarized?
The but monkey
# If the earth's surface is negatively charged, why aren't objects close to the surface polarized?

(Asked by: username_0 on 2021-02-20)

A lot of misinformation about earth and it being a sink is spread everywhere, including what I was taught in school, I hope you well-informed folk can help me out.

A *sort of* side-note, if anyone has a book recommendation explaining these kinds of concepts and everything related to them, please do let me know. It seems as if most books on electrodynamics don't really examine these assumptions we usually make. Examples: why earth is a 'sink' for electrons?; how, when grounding houses -- does a ground connection act as a wire which connects back to the same circuit, even when it's a [single wire](https://upload.wikimedia.org/wikipedia/commons/7/7d/HomeEarthRodAustralia1.jpg) (taken from [Ground](https://en.wikipedia.org/wiki/Ground_(electricity)) wikipedia page) connected to ground?
And the list goes on.

To quote my last question, I found it here: <https://electronics.stackexchange.com/a/148684>  
Quote:
"Current never ever ever ever flows *to* earth. It only ever flows *through* earth. Earth is just another wire - albeit a planet sized one. Electrons have to flow from one side of the power source back to the other. They can never flow out and never return." – Majenko

**Moving on, the original question**:
Why aren't objects close to the surface polarized?  
We know that by static inductance, when you rub two of the right materials together, one becomes negatively charged, and the other positively charged. Let's take one and get a neutrally charged material next to it, bringing it closer, we can see that it becomes polarized.

I've read that earth's surface is negatively charged, -500,000 coulombs, to be sure. So bringing a neutrally charged object close to it would make it polarized, is what I think is logical.

So why is my conclusion wrong, if it is wrong (doesn't seem right)? And why is it that earth is charged negatively?

**Tags:** electromagnetism


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## 2 answers

### Answer by username_1 on 2021-02-21. Score: 2

Think of the electric current as a fluid, and a battery or some other source of current as a pump. Change the earth for the ocean.

I don't know about the negatively charged earth's surface, but those -500,000 coulombs are an absolute measure of charge. That charge is distributed over some surface, and the earth's surface is pretty big.


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### Answer by username_2 on 2021-02-20. Score: 0

Yes, [the earth has a field strength.](https://hypertextbook.com/facts/1998/TreshaEdwards.shtml)

That page quotes field strength numbers of 300V/m or 150 newtons per coulomb. I've not bothered to do the equation for -0.5MC charge across the surface of the earth, but I expect it would line up with that.

The next question is why we don't notice this. I believe it's dominated by other effects; regular tribocharging can build up multiple-kilovolt charges on an ordinary human, and they don't notice until they touch a grounded object and get a small zap.


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