In electricity, you typically hear a lot more about amps than about colombs. Voltage and potential Voltage is analogous to hydraulic pressure. The unit is volts , and it's measured by a voltmeter . The metal chassis inside a TV used to be a 120 volt floating ground about half the time, depending on which way you plugged the TV into the outlet. In electricity, you hear a lot more about voltage than potential.
Voltage is an across variable.
We will revisit this rule again in the Loops and Junctions section. Batteries The power source we will most often use will be a battery - a constant voltage source. A battery has a rating indicating how many volts it supplies. Each battery has a positive terminal and negative terminal clearly marked. The voltage across is given by its stated voltage rating.