In an extracurricular activity, a classmate carried out relevant observation and Research on household appliances. He took a far infrared furnace as the observation and research object Observe the far infrared furnace name plate u = 220 V P = 1 kW 220v 10(40)A Observe the name plate of electric energy meter, 50 Hz 2000 revs / kW. H Heat a pot of water with a far-infrared electric stove, turn off other household appliances, and only connect the far-infrared electric stove to the circuit to boil water, Observe the watt hour meter. The dial turns 150 revs in 5 minutes. At this time, use the thermometer (mass of water M = 2kg, initial temperature T = 30 ℃) the measured water temperature is 50 ℃ Please answer the following questions about the information obtained by this student during the activity: (1) Heat absorbed by water after heating for 5 min. (2) The electric energy consumed by the far infrared electric furnace working for 5 minutes. (3) The actual voltage of far infrared furnace. (4) The voltage of the far infrared furnace is 220 V when it works normally. Try to calculate the resistance of the wire.

In an extracurricular activity, a classmate carried out relevant observation and Research on household appliances. He took a far infrared furnace as the observation and research object Observe the far infrared furnace name plate u = 220 V P = 1 kW 220v 10(40)A Observe the name plate of electric energy meter, 50 Hz 2000 revs / kW. H Heat a pot of water with a far-infrared electric stove, turn off other household appliances, and only connect the far-infrared electric stove to the circuit to boil water, Observe the watt hour meter. The dial turns 150 revs in 5 minutes. At this time, use the thermometer (mass of water M = 2kg, initial temperature T = 30 ℃) the measured water temperature is 50 ℃ Please answer the following questions about the information obtained by this student during the activity: (1) Heat absorbed by water after heating for 5 min. (2) The electric energy consumed by the far infrared electric furnace working for 5 minutes. (3) The actual voltage of far infrared furnace. (4) The voltage of the far infrared furnace is 220 V when it works normally. Try to calculate the resistance of the wire.

1 "220V 1000W" resistance R = U2 / P = (220V) 2 / 1000W = 48.4 Ω
The resistance of "220 V 500 W" r = U2 / P = (220 V) 2 / 500 W = 96.8 Ω, the resistance of half resistance wire is 48.4 Ω, which meets the rated power requirements of electric heating box
In practical application, the resistance of half resistance wire is 48.4 ohm, but such resistance wire is easy to burn out, so it is not suitable to use
3. The resistance wire of "220V 1000W" can be replaced by two sections of "220V 500W" heating wire in parallel

About induction cooker
Xiao Ming studied the induction cooker at home, and the power regulation range of induction cooker is 120W ~ 2200W
Q: Xiaoming uses an induction cooker to heat 2.5kg water from 20 ℃ to 100 ℃, consuming 0.28kw. H of electric energy. What is the heat absorbed by the water? What is the efficiency of the induction cooker?

Output energy: 4200 * 2.5 * (100-20) = 8.4 * 10 ^ 5 J
Power consumption: 0.28kwh = 1.008 * 10 ^ 6 J
Efficiency = 8.4 * 10 ^ 5 / (1.008 * 10 ^ 6) = 83.3%