Xiaowen and Xiaoli * * * measured the actual power and heating efficiency of the electric kettle when boiling water, and conducted the following experiments: turn off all household appliances, turn of

Xiaowen and Xiaoli * * * measured the actual power and heating efficiency of the electric kettle when boiling water, and conducted the following experiments: turn off all household appliances, turn off the electric kettle (1) According to ρ=mV, we can get:

Mass of water when the pot is full of water:

m =ρV = 1.0× 103kg/m3× 1× 10-3 m3 = 1kg，

Heat absorbed by water:

Q suction =c water m△t=4.2× 103J/(kg? ℃)× 1kg×(35℃-25℃)= 4.2× 104j，

Electric energy consumed by electric kettle filled with water for 50 seconds:

w = 403200×3.6× 106j = 4.5× 104j，

Actual power of electric kettle when boiling water:

p real = wt = 4.5× 104 j50s = 900 w；

(2) Heating efficiency of electric kettle:

η=Q absorption w×100% = 4.2×104J 4.5×104J100% ≈ 93.3%;

(3) According to the data, the rated power of the electric kettle is 1000W, while the actual power is 900W, probably because the actual voltage is less than the rated voltage.

Answer: (1) The heat absorbed by water is 4.2× 104J, and the actual power of electric kettle when boiling water is 900 W；;

(2) The heating efficiency of electric kettle is about 93.3%;

(3) The actual voltage is less than the rated voltage.