The maximum allowable current of a school's electric energy meter is 25A. The school has installed 50 40W electric lamps and 20 60W electric lamps. I want to install electric energy meter in the school How many can you press at least 40W

The maximum allowable current of a school's electric energy meter is 25A. The school has installed 50 40W electric lamps and 20 60W electric lamps. I want to install electric energy meter in the school How many can you press at least 40W

The voltage is 220 V and the current is 25 A
Maximum power P = UI = 220 * 25 = 5500w
Existing electric lamp power = 40 * 50 + 60 * 20 = 3200W
The number of 40W lamps can be installed = (5500-3200) / 40 = 57.5, about 57

As shown in the figure is a single-phase electronic multi rate watt hour meter. With regard to its technical parameters and functions, the correct one in the following description is ()
A. 220 V refers to the rated voltage applicable to the electric energy meter. B. 5A refers to the maximum current allowed to pass through the electric energy meter in a short time. C. 3200 & nbsp; imp / (kW · h) refers to the electric energy consumed by the electric appliance every 1 & nbsp; kW · H: the dial of the electric energy meter turns 3200 turns. D. the electric energy meter is an instrument for measuring electric power

A. 220 V means that the rated voltage of the meter is 220 V, which should be applied to the circuit with rated voltage of 220 V, so a is correct; B, 5A means that the normal working current through the meter can not exceed 5a, and 30A means that the maximum current allowed to pass through the meter in a short time is 30 A. so B is wrong; C, 3200 imp / (kW · h)

There is an electric energy meter, which is marked with 3000r / kW. H. The electric energy consumed by the circuit is（

15 / 3000 * 3.6 * 10 Λ 6 = self calculation