How many ordinary flashlight cells are needed to obtain 6 volts when connected together?

To determine how many ordinary flashlight cells are required to achieve a total voltage of 6 volts, it's essential to know the voltage rating of a standard flashlight cell. Typically, a standard alkaline flashlight cell (AA, AAA, etc.) has a nominal voltage of about 1.5 volts.

When cells are connected in series, their voltages add up. Therefore, to find the number of cells needed to reach 6 volts, we divide 6 volts by the voltage of one cell:

6 volts ÷ 1.5 volts per cell = 4 cells.

This calculation shows that connecting 4 ordinary flashlight cells in series will yield a total voltage of 6 volts. Hence, the correct choice indicates that 4 cells are necessary to achieve this voltage.