The voltmeter connected across a single battery in a series circuit displays the electromotive force (emf) of that single battery, not the sum of the emfs of both batteries. This conclusion is based on the understanding that a real battery can be modeled as an ideal battery in series with a small internal resistance, which affects the voltage reading under load conditions. Therefore, when measuring voltage, the voltmeter reflects the potential difference across the specific battery it is connected to.
PREREQUISITESElectrical engineering students, hobbyists working with batteries, and anyone interested in understanding voltage measurements in series circuits.