1.5 (6) a meter, 1 degree of electricity is equal to 15 degrees, the meter can withstand the maximum power

1.5 (6) a meter, 1 degree of electricity is equal to 15 degrees, the meter can withstand the maximum power

It should be said that one word stands for 15 degrees, then the transformer is 75 / 5
75A, about 50KVA

The primary power can supply the normal operation of "220 V & nbsp; & nbsp; 40 W" lamp ()
A. 10hB. 15hC. 20hD. 25h

Method 1: w = 1 degree = 3.6 × 106j, t = WP = 3.6 × 106j, 40W = 9 × 104s = 25h. Method 2: P = 40W = 0.04kw, w = 1 degree = 1kW · h, & nbsp; t = WP = 1kW · h0.04kw = 25h

How many hours can the "220 V 40 W" lamp work normally under 110 V voltage?

According to P = u & sup2; / R
The resistance of the bulb remains unchanged, the voltage is halved, and the power becomes 1 / 4
So the power of the lamp is 1 / 4 of the rated power at 110V, which is 10W, that is 0.01kw
According to w = Pt
t=W／P=1Kwh÷0.01Kw=100h

Is the power consumption of 220 V 20 W and 12 V 20 W bulbs the same?

The same power consumes the same power
Power = voltage * current p = u * I I = P / u
Same power 220 v current is small, can use thin wire. (20w0.091a)
Use thick wire for 12V current. (20w1.67a)