Question

В електричний чайник налили 0,5 кг води при температурі 12 градусів, через який час закипить вода в чайнику якщо сила струму в його нагрівальному елементі дорівнює 10А, а напруга в мережі становить 220В? ККД чайника становить 84%

Answer 1

КПД=Qпол/Qотд; Qпол=cm(t2-t1), t1=12град.; t2=100град.; Qотд=IUτ; КПД=cm(t2-t1)/IUτ; τ=cm(t2-t1)/IU*КПД; τ=100с. Ответ: 100с.

Answer 2

To calculate the time it takes for the water to boil in the electric kettle, we can use the formula:

Q = m * c * ΔT

Where: - Q is the heat energy required to raise the temperature of the water - m is the mass of the water - c is the specific heat capacity of water - ΔT is the change in temperature

In this case, the mass of the water is 0.5 kg and the initial temperature is 12 degrees Celsius. We need to find the time it takes for the water to reach its boiling point, which is 100 degrees Celsius.

First, let's calculate the heat energy required to raise the temperature of the water:

Q = m * c * ΔT Q = 0.5 kg * 4186 J/kg°C * (100°C - 12°C) Q = 0.5 kg * 4186 J/kg°C * 88°C Q = 184,568 J

Next, we need to calculate the power of the electric kettle's heating element. The power is given by the formula:

P = V * I

Where: - P is the power - V is the voltage - I is the current

In this case, the voltage is 220 V and the current is 10 A. Let's calculate the power:

P = 220 V * 10 A P = 2200 W

Now, we can calculate the time it takes for the water to boil using the formula:

Q = P * t

Where: - Q is the heat energy required to raise the temperature of the water (184,568 J) - P is the power of the electric kettle's heating element (2200 W) - t is the time

Let's solve for t:

t = Q / P t = 184,568 J / 2200 W t ≈ 83.89 seconds

Therefore, it will take approximately 83.89 seconds for the water to boil in the electric kettle.

Please note that this calculation assumes ideal conditions and does not take into account any heat loss to the surroundings.