Why is the top of a dry cell battery always marked with a plus sign?
It isn’t always the “top”. Pick up the battery and turn it a different orientation and it is no longer the top. Its proper name is the positive terminal. The opposite side is the negative terminal. At the positive terminal, electron deficits form as the electrochemical reactions occur. Electron deficits mean a positive net charge in said region, and thus a higher voltage than the negative terminal. We defined the electron to be negative as per artifacts of history, and thus electron deficient regions are positive. At the negative terminal, surplus electrons gather as the electrochemical reactions occur. This means a net negative charged region and a lower voltage than the positive terminal. Hence we mark it wit a minus sign. We orient the positive terminal typically at the top when drawing the diagrams, because people who work with electrical circuits prefer to see positive charge, the current, flow “downhill” external to the voltage source when drawing the diagram, even though externa
