What is current and voltage of power adapter? First, open circuit output voltage formal be called voltage, as well as the outside of the adapter not connect with any load. without current output, it means the voltage is limit of adapter.
For use inside the power supply under the condition of the active voltage components, even if the mains voltage fluctuation, the output is also a constant value, as the market of small transformers, like the walkman with power supply, if the mains fluctuation, the output of the power supply will not then swings.
In general ordinary real no-load voltage power adapter does not necessarily completely consistent, and nominal voltage because of the characteristics of electronic components can't completely consistent, so there is a certain error, error is smaller, the higher the consistency requirements for electronic components, the production cost is high, so the price is expensive.
In addition, about the nominal current value, regardless of any power supply has a certain amount of resistance, so when the power supply output current, can produce the pressure drop in the internal, lead to two things, one is to generate heat, so the power supply will be hot, another is the results in the decrease of the output voltage, equivalent to the internal consumption.