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1) It is most unlikely that you have a linear power supply for a laptop. It is most likely that it is a non-linear power supply. The non-linear ones convert the incoming power to "dc", then uses a solid state circuit to raise it to an HF frequency, use a tiny hf transformer to raise the voltage, a rectifier back to dc, and a voltage regulator to set the proper output voltage.
I've been in the computer business since before PC and laptops. I have never seen a linear [transformer -- rectifier] brick power supply for a laptop.
2) These power supplies are usually voltage and frequency agile: 50-60Hz, 100-250VAC inputs without any manual adjustments, so they can be used on "mains" power in virtually any place on earth.
3) I took a 1/2 dozen different laptop supplies of different companies and a WattStopper? plug in meter.
All six read 0.00 W, 0.00KwH. and 0.00VA on 124.5V. They had an inrush current of .5A ? .05A as registered on the meter. They had a steady state reading of 0.01A.
This high inrush current versus unloaded current is indicative of non-linear power supplies. Transformers have a higher inrush than unloaded current but not at this high a ratio.
The wattage, assuming unity power factor would be 1.25W, at 10?/KwH, it would take 80 hours to waste a penny.
Hope this helps!
[This is all based on the 100% accuracy of the meter
]