Why Do Voltages in Series Add: Explained Physically

[elm-chris]

Why do voltages in series add? I would like to have this explained physically. Most answers I get are something like: "Because in a parallel circuit the voltage is constant." I have memorized the concept but want to try and learn why this is so. What physically goes on with the circuit to make the voltages add.


Thanks

 

[Nabeshin]

Okay take the case of two batteries in series each with a voltage V. What this voltage means is that the potential different between the two nodes of the battery is V. So imagine a circuit connecting these two batteries in series and follow the current. Let's s say we're going up in potential as we cross batteries. So first we're at zero volts. Then we hit the - terminal and to get to the + terminal is V volts. so we're at +V volts overall. Now we hit the - terminal of the next battery and again to go to the + terminal on this battery is +V volts. So we see that the total voltage of the circuit is 2V.

Not sure if this is the kind of explanation you were looking for, but there it is.

 

[dst]

It's called a "potential difference" for a reason. No different than, for example, a ball being at a height h above the floor vs the same ball being at a height 2h. In the latter case, there is double the potential energy with respect to the floor.

 

[jbunten]

To add what the above posters have said, think of it in terms of work required to move a unit of charge, say one Coulomb. If you have two voltages in series and you are a charge moving through a circuit, work is done on you to move you across the first PD, then across the second PD, and since work is a scalar you just add it up - the total work done would have been the same as if it were just one PD.

I hope that's clear..