Voltage

• Voltage is the force of the electric current. It is important to understand that it is not the amount of energy or electricity in the wire, but the force at which it's being pushed through the circuit. Voltages change depending on the source of the power. Vehicle car batteries operate at 12 volts, standard American outlets operate at 120 volts, and electric dryers and ranges require 240 volts. This is not standard throughout the world; some countries follow different voltage standards.
  
  

AC and DC Power

• With AC power, the voltage swings from +120 volts to -120 volts each cycle; one cycle can be 1/50 to 1/60 of a second. AC power is used because, in power transmission, it is more efficient than DC power. It is also used because higher-power electrical motors can only run only AC power. DC power is generated using batteries and other small energy sources. DC power is simply one current and one voltage that does not fluctuate or change.
  
  

Power Inverter

• A power inverter is a device designed to convert DC power to AC power or vice versa. These devices are commonly used to allow a DC car lighter outlet to be inverted into an AC power source. These devices are also used in portable generators, but are embedded into the generators. Inverters can also be used to covert AC to DC power, such is the case with cell phone chargers, which convert the 120-volt AC outlet energy to match the DC voltage rating of your cell phone battery.
  
  

Power Converter

• A power converter is a device designed to convert voltage. This process is known as stepping-up or stepping-down voltage. Converters are used on a consumer level, such as a device designed to convert European outlet voltage to North American outlet voltage. They are also used on a professional level -- power that is generated at a hydro plant will be stepped-down numerous times by converters before it reaches your house.