Caption: Series electric circuits. Animation showing the principle of electric circuits connected in series, and the measurement of electric current and voltage. The animation starts with a schematic view of an electric circuit, showing the power source (electric cell, or battery) at top. At lower left is an ammeter ('A' symbol), used to measure electric current in amperes (amps). At lower centre, connected across the component drawing electric current, is a voltmeter ('V' symbol), used to measure the potential difference in volts. The component drawing power in this case is an electric lamp ('cross' symbol). The start of the animation shows electric current (blue dots) flowing around the circuit, causing the electric lamp to light up. An initial voltage reading is shown as 2 volts. With three 2-volt batteries (top) the voltage increases to 6 volts. Returning to the 2-volt battery, the addition of an extra light bulb connected in series results in the voltage dropping to 1 volt across each light bulb. With three, it is two-thirds of a volt or 0.67 volts. The second half of the animation shows the electric current measurements. Initially, with one lamp and a 2-volt battery, it is 0.30 amps. With a 6-volt battery, the electric current is 0.90 amps. Returning to the 2-volt battery, with two light bulbs the electric current for each component is halved to 0.15 amps, and reduced again to 0.10 amps with three light bulbs. The total amount of electric current stays the same. The end of the animation shows the measurements with three 2-volt batteries with a total voltage of 6 volts and 2 volts across each light bulb, and 0.30 amps each (total current of 0.90 amps). The basic principle is that the voltage drops as more devices are connected in series, with the overall current staying the same. i.e. For series circuits, the current stays the same but the voltage decreases. For the principles of circuits connected in parallel, see clip K005/6744.