**1. The problem statement, all variables and given/known data**

How can I measure the potential difference across two batteries? For example, if I put the batteries end to end, so the negative end of one touches the positive end of the other. And lets say both batteries have 3 volts and lets denote point A to B as the point from one battery to the other.

**2. Relevant equations**

##\Delta V = -\int^b_a\vec{E} \dot\ \vec{dL}##

**3. The attempt at a solution**

So if the length of both batteries is 5 cm then do I put a point C in the middle of the two batteries and measure the potential difference separately from point A to point C then from point C to point A?

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