The rated current of a school's electric energy meter is 25A. The school has installed 50 40W electric lamps and 20 60W electric lamps. If you want to install more electric lamps, how many 40W electric lamps can you install at most?

The rated current of a school's electric energy meter is 25A. The school has installed 50 40W electric lamps and 20 60W electric lamps. If you want to install more electric lamps, how many 40W electric lamps can you install at most?

If the voltage of lighting circuit is 220 V, the total power of bulb allowed to work at the same time is p = 220 V × 25 A = 5500 W, the total power of installed bulb is p ′ = 50 × 40 W + 20 × 60 W = 3200 W, the total power allowed to increase is P ″ = P-P ′ = 5500 w-3200 w = 2300 W, the number of bulb allowed to increase 40 W is n = P ″ P0 = 2300 W, 40W = 57.5, that is 57 Install another 57 40W lamps

One watt hour meter is marked with 220 V 5A 50 Hz

220 V refers to the voltage; 5 a refers to the current; 50 Hz refers to the AC frequency of the meter

A certain electric energy meter is marked with 3000r / kW. H. When a certain electric appliance is used alone, the dial of the electric energy meter turns 10 turns within 600s, then the electric energy consumed by the electric appliance is

First of all, we should know that the electric energy consumed by the dial for one revolution is: 1kW · H / 3000 = 3.6 × 10 to the sixth power, J / 3000 = 1.2 × 10 & # 179; J
Then the power consumption of 10 revolutions is: 1.2 × 10 & # 179; J × 10 = the fourth power of 1.2 × 10

The words (1500r / kW * h) are marked on the electric energy meter. It is observed that if the rotary table of the electric energy meter turns 60 turns within 10 minutes, how much electric energy is consumed per minute?

W=60/1500=0.04kW.h
The average power consumption per minute of the consumer is:
0.04/10=0.004kw.h