If two sources are connected in series in the same orientation, the total applied voltage is

• A. The largest single voltage
• B. The difference between voltages
• C. It depends on the load
• D. The sum of the voltages

Answer: (D)

When two voltage sources are connected in series in the same direction, the potentials add up. Each source contributes its emf in the same orientation, so the total voltage across the combination is the sum of their voltages. For example, two equal sources in series give twice that voltage across the circuit. The load affects how much current flows, not the total applied voltage provided by the sources themselves. If the sources have internal resistances, the current is determined by the total emf divided by the total resistance (including those internal resistances), but the total available voltage across the external circuit remains the sum of the source voltages.