If L1, L2 and L3 are marked with "220V & nbsp; 100W", "110V & nbsp; 100W" and "36V & nbsp; & nbsp; 100W" respectively, and they all light normally, then () A. L1 is the brightest B. L2 is the brightest C. L3 & nbsp; is the brightest D

If L1, L2 and L3 are marked with "220V & nbsp; 100W", "110V & nbsp; 100W" and "36V & nbsp; & nbsp; 100W" respectively, and they all light normally, then () A. L1 is the brightest B. L2 is the brightest C. L3 & nbsp; is the brightest D

It is known from the title that the rated voltage of the three bulbs is different, but the rated power is the same, and they are all in the normal light-emitting state, so the actual power is equal to the rated power, and the rated power is equal, so the actual power is equal. That is, the bulbs are the same bright. So choose D

One kilowatt hour power can supply two 220 V 40 W bulbs to work normally for 12.5 hours. If these two lamps are turned on less than half an hour a day on average, 30 kilowatt hour power can be saved

Less than half an hour a day, that is 0.5 hours, this 0.5 hours of electricity
W = Pt = 0.04kw · 0.5h · 2 = 0.04kw · h, that is 0.04 kwh / day
The total energy saving is 30 × 0.04 kW · H = 1.2 kW · h, i.e. 1.2 kwh