Two different metals in a liquid create electricity because each metal releases electrons at a different rate. When zinc and copper sit in separate nitrate solutions divided by a porous cup, that unequal electron release drives voltage through the connecting wire. By building simple cells using zinc, copper, and lead sheets — each in its own nitrate solution — and testing all three pairings with a voltmeter, you discover which combination produces the strongest electrical output.

The reactivity series predicts battery voltage based on how far apart two metals sit in the ranking — metals with a larger gap push electrons more forcefully through a circuit. To test this, you build simple electrochemical cells using zinc, copper, and lead sheets, each sitting in its own nitrate solution with a porous cup separating the two halves. After connecting wires to a voltmeter and recording the readings for all three pairings, the zinc-and-copper combination produces the highest voltage output.

Different metal pairings produce different amounts of push when you build an electrochemical cell. You place zinc, copper, and lead sheets in their own nitrate solutions, separated by a porous cup, then connect wires to a voltmeter and record the reading for each combination. The metal pairing controls how much voltage the cell produces, so each reading differs. By testing all three pairings, you discover which metals generate the highest voltage output.