What is the total voltage of a series circuit using 3 D cells?

The total voltage of a series circuit using three standard D cells is 4.5 volts. A typical D cell supplies about 1.5 volts, and cells connected in series add their voltages: 1.5 + 1.5 + 1.5 = 4.5 volts.

In a series connection, the positive terminal of one cell is connected to the negative terminal of the next. The combined battery therefore has a higher total potential difference than any single cell. The current passes through the cells in sequence before reaching the rest of the circuit.

D describes the physical size and capacity class of the cell, not a different basic voltage. Standard alkaline and zinc-carbon D cells are commonly rated at 1.5 volts, although their actual voltage can vary with chemistry, load, temperature, and state of charge.

This result would change if the cells were rechargeable types, because many rechargeable cells are rated at about 1.2 volts each. Three such cells in series would normally provide about 3.6 volts nominally. The quiz's 4.5-volt answer assumes ordinary 1.5-volt D cells.