I understand why you get harmed if you’re grounded, you’re becoming part of the wire and the electricity is going from you to the earth. what I dont understand is, why the electricity doesnt harm you when youre not touching the ground, isnt it going through you either way? how does it not affect your body?
In: Physics
Imagine a dam which is holding back water at a certain height. Now imagine two different additions to the dam: the first is an extension to the dam (imagine like a U-shaped section built onto the outer wall) that’s the same height as the rest of the dam. If they then open the extension up to the reservoir, a bit of water will obviously fill the extension but there won’t be any sustained flow, as all the water does is essentially shift a bit.
The second addition is another extension, but now the wall is much lower than the original dam height. If they open that extension up to the reservoir, the water will end up crashing down and overflowing the shorter wall, leading to a sustained flow until either the reservoir is closed off again or the water equalizes in height on either side.
The second example is the equivalent of grabbing a power line while grounded. The Earth can basically be thought of as having an electric potential of 0 Volts, while the power line has a much much higher potential, similarly to a tall dam that’s holding back a huge amount of water with a ton of potential energy. If you grab the line while not connected to the Earth, you provide a small place where the electrons rush in initially, but as you’re not connected to anywhere the electrons can escape to easily, you eventually equalize with the potential in the wire and the flow stops very quickly. Your body would now be at the same voltage as the line and there would be no net “pressure” that would cause the electrons to move through you, just the pressure of the resistance of the air/your rubber shoes equaling the pressure coming from the nearby transformer/substation.
But when you’re grounded, your body will now have a potential difference, where it’s 0 Volts at your feet due to the Earth being at 0 volts and however many hundreds of volts at your hand or wherever it’s touching, and like the dam that’s mostly a very high wall but is now open to a section of low wall, the electrons will want to move to the lower potential and are able to maintain a sustained flow until the connection is broken or the voltages equalize, neither of which would probably happen before you take massive damage through the path of the flow.
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