Voltage

Electrons flow from a point of higher negative charge to the lower negative one. This difference between the charge two points is called voltage. It is measured in volts (symbol: V). Voltage and the term potential difference are often used interchangeably. The potential difference might be better defined as the potential energy difference between two points in a circuit. The amount of difference (expressed in volts) determines how much potential exists in energy to move electrons from one specific point to another. Voltage and current are directly related. All other parameters being equal, the higher the voltage the higher the current.

A household battery, for example, provides 1.5 volts and a direct current. Typical household electrical outlets provide 110-240 volts and an alternating current. The greater the voltage in a circuit, the greater its ability to push more electrons to do work. An alkaline battery of 1.5 volts would probably be sufficient for a device where very little electron flow is required. For example, the minimum voltage required for the simplest of devices such as a remote control or a small flashlight is 3 volts or two alkaline batteries. Slightly bigger devices may need 9 volt batteries. Light bulbs and bigger appliances, such as washing machines and microwave ovens, need 110-240 volts and alternating current.