There is sentence in my seminar about electric. I am not sure I understand correct or not. Thank much?

Question

I am not native English. There is sentence in my seminar: “Tips to save energy at you home”. I am not sure I understand correct or not. Please help me to explain. Thank you very much.

Original sentence:
Plug anything that can be powered by a remote control or that has a power cube transformer (little black box) into a power strip, and turn it off, and/or unplug, when not in use. (Power cubes are 60-80 percent inefficient.)
I understand that 
- When we first power off TV by remote control, we should unplug then to save energy. And when we charges battery (laptop, mobile…), when battery is full, we also unplug from power strip, so that we can save energy.
- “Power cubes are 60-80 percent inefficient”: means when battery is full, if we still plug into power strip, there is only 60-80% still in not using… But we waste remain 20-40% energy.
- Power cube transformer and Power cube is same ??? I understand them as battery charger (of mobile, camera and others)

Anonymous · Accepted Answer

The little black box or power cube is simply a transformer and power supply which changes the 240 volt ac current in the house to the lower, usually 12 volt dc current which the device will use. Whether the power cube powers the device or merely charges it is determined by the cube's output and the way it is regulated. Not so long ago there were no such things as "power cubes" the power supply being built into the devices themselves. This was much more efficient because the whole device was off and used no current at all when it was switched off. With a power cube a lot of energy is wasted because the cube itself still draws mains voltage even though the device it is powering is switched off. A rather backward step for the sake of fashion, I think you would agree!

There is sentence in my seminar about electric. I am not sure I understand correct or not. Thank much?

1 Answer