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9:31 AM
@JohnRennie, Hi sir :-)
May I ask a doubt related to "electrical earthing"?
 
@M.GuruVishnu what did you want to ask?
 
In my book Earth is said to be a very good conductor of electricity. Is it really a very good conductor? Many sources say that earth conducts electricity due to water and ions present in them. So it is a conductor but how can it be a very good conductor, sir? Further, is it a good conductor compared to most of the metals sir?
 
No, it isn't a good conductor. But it has a large cross sectional area. Remember that $R = \rho L/A$ so a large area means a low resistance even if $\rho$ is high.
 
@JohnRennie But earth cables are not of the radius of earth. Then why do we rely so much on these cables to prevent electric shock sir?
Or more precisely, the area of contact of the copper rod is not that large to make a significant contribution.
 
9:49 AM
I don't know how the earth connections are configured in real circuits.
 
You mean zero potential? @M.GuruVishnu
 
@JohnRennie In my book it's given, a copper rod is buried deep inside the ground. Will this help sir?
 
@M.GuruVishnu well it increases the area of the copper-earth interface ...
 
@JohnRennie Yes sir. But I think it's not comparable to the earth's dimensions.
 
Well it obviously works
 
9:52 AM
@JohnRennie Yes sir :) It works, but how?
 
Don't know.
 
@JohnRennie Ok sir. May I ask a last question?
 
Yes
 
@JohnRennie: When someone touches a power outlet standing on a concrete floor, he receives electric shock. How does concrete being an insulator conduct electricity sir? Further, I think it's not possible to complete a circuit using a concrete rod instead of a copper wire.
 
Maybe your capacitance is big enough for charge to flow on and off you ...
Basically I don't know. You'd have to Google for details f exactly how current flows in this case.
 
10:03 AM
@JohnRennie :I tried that sir. I looked for conductivity of concrete, and other related questions. Even in PSE there was a similar question, but the answers don't address these. Only then I asked you sir.
This was the question I found most relevant:
3
Q: Why do we get electric shocks when most structures are insulators?

KarnivaurusSuppose I was standing in the sea, and touched an electric fence; I would receive an electric shock, because both my body and the sea are conductors, and create a path for the electricity to flow. The sea is so big that it has the capacity to draw and dissipate a great quantity of charge. However...

As yuvraj suggested, maybe the current drawn could lead to heating effects. But what happens in the case of concrete remains a mystery.
 
10:23 AM
@JohnRennie, Any suggestions on what to do next sir?
 
@M.GuruVishnu I'm tied up with Dante's code I'm afraid ...
 
@JohnRennie I understand. It's difficult to jump between C (or C++) to physics. Please reply after debugging sir.
OK sir?
 
@M.GuruVishnu, sorry I am. Asking this what else you want?
 
 
1 hour later…
11:54 AM
@yuvrajsingh Need some clarification regarding the subject of discussion with John Rennie sir.
Thanks.
 
 
1 hour later…
user439435
1:06 PM
@JohnRennie Sir can you answer this question: <br\>
https://physics.stackexchange.com/q/519694/238497
 
1:51 PM
I have got a problem with Lorentz force law, can anyone help me?
 
2:23 PM
Hi
 

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