插頭如果持續插插座會用電嗎？

In the IDEAL case, since there was no closed circuit, there will be no power used.

But there are energy loss in the daily life. You can feel your transformer is warm even the transformer was not in use. Transformer works by the use of changing magnetic field induction between the primary and secondary coils.There are loss in magnetic field in the primary coil even there was no loading in the secondary coil. Energy are lost.

No用電。
沒有電路can't耗電。
Because you haven't 用電於充電器

你無開個主開關既話都應該唔會用電。

不用電。沒有回路不會耗電。