Question

яка кількість теплоти виділяється за 20 хв в електронному чайнику опором 100 Ом, якщо його ввімкнути в мережу 220 В? Яка маса води налитої в чайник, якщо вона нагрілася за цей час від 20⁰C до кипіння?​

Answer 1

I = U / R.

I =  220 / 100 = 2.2 A

t = 20хв = 1200 с

Q = 2.2 * 220 * 1200 =580800 Дж

с = 4200 Дж/(кг*оС)

t1-t2 = 100-20=80 oC

m  = Q / (c * 80) = 580800 / (4200 * 80) = 1.7 кг.

ВІДПОВІДЬ: 1,7 кг.

Answer 2

To calculate the amount of heat generated in the electric kettle and the mass of water heated, we can use the formulas for electrical power and heat transfer.

Calculating the heat generated in the electric kettle:

The electrical power (P) can be calculated using the formula: P = V^2 / R where: - P is the power in watts (W) - V is the voltage in volts (V) - R is the resistance in ohms (Ω)

Given that the voltage (V) is 220 V and the resistance (R) is 100 Ω, we can calculate the power (P) using the formula.

P = (220^2) / 100

Using this formula, we find that the power generated in the electric kettle is 484 W.

Calculating the amount of heat generated:

The amount of heat (Q) generated in the electric kettle can be calculated using the formula: Q = P * t where: - Q is the heat in joules (J) - P is the power in watts (W) - t is the time in seconds (s)

Given that the time (t) is 20 minutes, we need to convert it to seconds: t = 20 * 60

Using this formula, we can calculate the amount of heat generated in the electric kettle.

Q = 484 * (20 * 60)

Using this formula, we find that the amount of heat generated in the electric kettle is 580,800 J.

Calculating the mass of water heated:

The amount of heat transferred to the water can be calculated using the formula: Q = m * c * ΔT where: - Q is the heat in joules (J) - m is the mass of the water in kilograms (kg) - c is the specific heat capacity of water, which is approximately 4.18 J/g°C - ΔT is the change in temperature in degrees Celsius (°C)

Given that the initial temperature (T1) is 20°C and the final temperature (T2) is the boiling point of water, which is 100°C, we can calculate the change in temperature (ΔT) using the formula: ΔT = T2 - T1

Using this formula, we find that the change in temperature is 100 - 20 = 80°C.

Now, we can calculate the mass of water (m) using the formula.

Q = m * c * ΔT

580,800 = m * 4.18 * 80

Simplifying the equation, we find that the mass of water heated is approximately 1745 grams or 1.745 kilograms.

Therefore, the amount of heat generated in the electric kettle is 580,800 J, and the mass of water heated is approximately 1.745 kilograms.