I was not able to understand the solution to the problem 2.37(a) of the 2nd chapter - "Electrostatic Potential and Capacitance".

Why do the equipotential surfaces of open air change when a person comes out of his house?

Asked by Rohan Rawal | 12th May, 2014, 09:21: PM

Expert Answer:

Near the surface of earth, the electric field is about 100 V/m and it is directed towards the ground (as shown by black lines). The equipotential surfaces are perpendicular to electric field lines (as shown by red dotted lines)
Since our body and the surface of earth, both are conducting , therefore, our body and the earth form an equipotential surface.
When we step out into the open from our house, the original equipotential surfaces of open air change, keeping our body and the ground potential at the same potential ( i.e. potential of person V = 0 ).
Hence the field lines get redistributed as shown in the diagram.
Now the current due to flow of electrons from clouds have two paths.
1) to ground through human body .
2) to ground directly.
But the resistance of human body is higher than the ground. Hence the electrons tend to take direct path and the person don't get electric shock.

Answered by Ravindra Kapal | 13th May, 2014, 04:38: PM

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