# How electrically common points have same voltage

Discussion in 'General Electronics Chat' started by ivepoli, Apr 20, 2016.

1. ### ivepoli Thread Starter New Member

Apr 19, 2016
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0
Hello,
I read about voltage in capacitor and see that voltage is dependent on distance from the two plates, like gravitational potential energy depends on height.
But how do electrically common points in circuit have the same voltage? Isn't voltage dependent on location in wire?

2. ### SLK001 Well-Known Member

Nov 29, 2011
849
242
It is for AC, but not for DC. What are you talking about?

3. ### mcgyvr AAC Fanatic!

Oct 15, 2009
4,787
973
They don't.. There is no voltage across 2 common points as they are connected

4. ### SLK001 Well-Known Member

Nov 29, 2011
849
242
It's not the voltage, but the capacitance that is dependent on the distance between the two plates. The voltage doesn't vary.

5. ### wayneh Expert

Sep 9, 2010
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3,226
Right, if there is a conductive path between two points, meaning they're common, any voltage imbalance causes current to flow and the imbalance quickly disappears. Like water seeking a level, only much much faster.

6. ### hp1729 Well-Known Member

Nov 23, 2015
2,086
232
Very low resistance along the wire thus very little difference in voltage. There is a difference but your meter could not measure it.

7. ### AnalogKid Distinguished Member

Aug 1, 2013
4,685
1,297
Yes, but the difference usually is microvolts, too small to measure and way too small to care about.

Technically, most of the time two points in a circuit are connected there is electron flow (current) from one point to the other. But copper is an excellent conductor, and the resistance in the copper connection is so small relative to the energy being moved that the voltage difference is hard to measure. Microvolt meters and micro-ohmeters are designed specifically for these kinds of measurements.

ak