Electricity has some similarities to water, so to help understand this question, you can consider what happens to water when the valve is closed, says Kurt Broderick, research specialist at the Microsystems Technology Laboratories. The electricity, like water on a closed valve, exerts a pushing force on the outlet, but instead of being called pressure, it is called volts.
When certain devices, such as standard incandescent lamps or can openers, are unplugged or off, there will be no flow (amps) moving through the outlet. “The electrons don’t move, any more than the water does when the taps on the sink are closed, and thus there is no work done,” Broderick says.
But not all electrical devices are dormant just because they are not performing their primary function. A microwave with a clock, for instance, uses as much power as a clock when it is plugged in, and a phone charger with a transformer is using a minute amount of electricity. – Deborah Halber