We use an electric immersion heater to heat 2,0 liters water having temperature of 20C to the boiling
point. Specific heat capacity of water is 4,19 kJ/(kg c). The power of the heater is 1,50 kW and efficiency
of heating is 80 %. How much time does the heating take?
power= mc*deltatemp/time
tme= mc*deltaTemp/power
= 2kg*4.18kJ/kgC*80C/(1200watts*.8)
time will be in seconds.
To calculate the time it takes to heat the water using an electric immersion heater, we can use the formula:
Q = mcΔT
Where:
Q = amount of heat energy transferred
m = mass of water
c = specific heat capacity of water
ΔT = change in temperature
First, let's calculate the amount of heat energy transferred:
Q = mcΔT
Q = 2000g * 4.19 kJ/(kg°C) * (100°C - 20°C)
Q = 2000g * 4.19 kJ/(kg°C) * 80°C
Q = 2000g * 335.2 kJ
Q = 670,400 kJ
Next, we need to calculate the amount of electrical energy used by the immersion heater:
Electrical Energy = Power * Time
Since the efficiency of heating is given as 80%, we need to calculate the effective power used:
Effective Power = Efficiency * Power
Effective Power = 0.80 * 1.50 kW
Effective Power = 1.20 kW
Now, rearranging the equation for Electrical Energy, we can solve for time:
Time = Electrical Energy / Effective Power
Plugging in the values:
Time = 670,400 kJ / 1.20 kW
Time = 558,666.67 seconds
So, it would take approximately 558,666.67 seconds to heat the water to the boiling point using the given electric immersion heater.