Question

электрический чайник нагревает воду объёмом V=2,0 л от температуры t=12градусов по цельсию до кипения за время t=10 минут . орпределите сопротивление спирали электрическогот чайника расчитанного на напряжение U=220в коэфицент полезного действия чайника n=70% (удельная теплоёмкасть воды с=4200 плотность воды р=1000 )

Answer 1

V=2л
t1=12град.
t2=100 град.
Т=10мин=600сек
U=220В
КПД=70%
С=4200
р=1000
Найти R-?
Qполное=сm(t2-t1)=cpV(t2-t1)=4200*1000*2*(100-12)=739 200 000 Дж (кол-во теплоты необходимое для нагрева воды)
Qобщ=Qпол/КПД=739 200 000/0,7= 1 056 000 000 Дж
Q=(U^2*T)/R
R=(U^2*T)/Q=(220^2*600)/1 056 000 000 = 0,0275 Ом

Answer 2

Calculation of the Resistance of the Electric Kettle's Heating Element

To determine the resistance of the heating element in the electric kettle, we can use the formula:

R = (U^2 * t) / (n * V * (t_boiling - t_initial))

where: - R is the resistance of the heating element, - U is the voltage (220 V in this case), - t is the time taken to heat the water (10 minutes or 600 seconds), - n is the efficiency of the kettle (70% or 0.7), - V is the volume of water (2.0 liters or 2000 cm^3), - t_boiling is the boiling temperature of water (100 degrees Celsius), and - t_initial is the initial temperature of the water (12 degrees Celsius).

Let's substitute the given values into the formula and calculate the resistance.

Step 1: Convert the volume of water from liters to cubic centimeters (cm^3): - V = 2.0 liters = 2000 cm^3

Step 2: Convert the initial temperature from Celsius to Kelvin: - t_initial = 12 degrees Celsius = 12 + 273.15 Kelvin = 285.15 Kelvin

Step 3: Substitute the values into the formula and calculate the resistance:

R = (220^2 * 600) / (0.7 * 2000 * (100 - 12))

R = (48400 * 600) / (0.7 * 2000 * 88)

R = 29040000 / (0.7 * 176000)

R ≈ 244.86 ohms

Therefore, the resistance of the heating element in the electric kettle, calculated based on the given parameters, is approximately 244.86 ohms.