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I must say that electricity is hard to grasp conceptually. Just when it makes sense, you think hard about it and it all becomes confusing.

When someone says electricity takes the path of least resistance, it never made much sense. Consider you have a light bulb and one of the wires connecting to it is bare and the bulb is on. If I touch the bare wire, I will get a shock and it will travel through my body to the ground. I can understand this if I cut the bare wire and connected myself in series with the bulb. There is no where for the electricity to go. But when I touch the wire, I am in parallel with the bulb. The bare wire has less resistance so shouldn't the electricity bypass my body and go straight to the ground terminal? There's less resistance to get there as opposed to going through my body which is very resistant.

What is so special about ground (the floor) that electricity goes to it. How can it possibly complete the circuit?

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Electricity does not take the path of least resistance - it flows more through lower resistances and less through higher resistances. If you had a 10V battery feeding two parallel resistors and, the resistors were 10 ohms and 1000 ohms, 1 amp would flow through the 10 ohm resistor and 10mA would flow through the 1000 ohm resistor. It's called ohms law: -

Current = Voltage/Resistance or I = V/R

With mains voltages, current quite easily flows through the body and gets to ground via slightly conductive floors. Current can also flow due to body capacitance to ground due the mains voltage alternating at 50/60 Hz.

Because (usually) most AC supplies get grounded at the sub-station down the street, the return path is "guaranteed".

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It doesn't exclusively follow the path of least resistance. Consider a 100W bulb and a 40W bulb on the same circuit. Both will light up, though the 40W bulb clearly has more resistance, draws less current, uses less power, etc. Now replace the 40W bulb with your finger...(*)


(*) I'm sure you know, but because this is public and there are stupid people around, DON'T ACTUALLY DO THAT!!!

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