Voltage> Italian scientist Alessandro Volta invented the first <#5962,11><!battery>. So his name went down in electric fame as the “volt.” What’s a volt? Check the batteries in your home. The label tells what the battery’s voltage is: 1.5 volts or 9 volts, for example. A battery gives electric charges the energy they need to move through circuits. The more volts, the more energy!
A few batteries with 1.5 volts can run a flashlight or a radio. The electricity in your house is a shocking 110 or 220 volts. That’s supplies enough current to stop a human heart. (An excellent reason not to play with electric sockets, or anything plugged into them!)
A <#5629,5137><!voltmeter> is a tool that measures the voltage difference (the difference in energy) between any two places. You can measure the voltage difference between the two terminals of a battery, or between two points in any circuit.
You can even measure the voltage difference between two points in an incomplete circuit (like the one made by the two 1.5 Volt batteries in the picture). Notice how the voltage of the batteries adds together, to make a total difference of 3 Volts? When you connect opposite terminals of different batteries, their energy combines together.
