Question

Электрический нагреватель, который включают в сеть напряжением 220 В, нагревает чай за 3 мин 30 с. Нихромовую спираль заменили фехралевой того же размера. Сколько времени теперь займет нагревание чая? Удельные сопротивление нихрома 1,1 Ом*м / мм квадратный, а фехраля- 1,3 Ом*м / мм квадратный. Потери энергии не учитывайте. Помогите,пожалуйста.

Answer 1

Q1=P1*t1=U^2*t1/R1=U^2*t1/(ro1*L/S)
Q2=P2*t2=U^2*t2/R2=U^2*t2/(ro2*L/S)
Q1=Q2 =>
U^2*t1/(ro1*L/S) = U^2*t2/(ro2*L/S)
t1/ro1 = t2/ro2
 t2 = ro2/ro1 *  t1 = 1,3/1,1 * (3*60+30) сек = 248,1818 сек ~ 4 мин 8 сек

Answer 2

По закону Джоуля-Ленца Q=U^2*t/R.  Находим  Q1 = 220*220*210/1,1*10^-6= 924*10^10Дж (210 - это время в сек, 1,1*10^-6 - удельное сопротивление в СИ)
 (заменяем R на р - удельное сопротивление, т.к. остальные параметры проводников одинаковые).
 Выражаем t2=Q*р2/U^2=924*10^10*1,3*10^-6/220^2=248,18*10^4с=4,1 мин. 

Answer 3

Calculation of Heating Time

To calculate the new heating time for the tea using a FeCrAl (фехраль) spiral instead of a nichrome (нихром) spiral, we need to consider the specific resistances of the two materials.

The specific resistance of nichrome is given as 1.1 Ω*m/мм², while the specific resistance of FeCrAl (фехраль) is given as 1.3 Ω*m/мм².

Since the size of the spiral remains the same, we can assume that the resistance of the FeCrAl (фехраль) spiral is also the same as the nichrome spiral.

To calculate the heating time, we can use the formula:

Heating time = (Resistance * Time with Nichrome) / Resistance with FeCrAl

Let's calculate the heating time using this formula.

Given: - Voltage: 220 V - Time with Nichrome: 3 minutes 30 seconds = 210 seconds - Specific resistance of nichrome: 1.1 Ω*m/мм² - Specific resistance of FeCrAl (фехраль): 1.3 Ω*m/мм²

First, we need to calculate the resistance of the nichrome spiral using the formula:

Resistance = (Voltage^2) / Power

Since the power is not given, we can assume it to be constant for both the nichrome and FeCrAl (фехраль) spirals.

Let's calculate the resistance of the nichrome spiral:

Resistance with Nichrome = (220^2) / Power

Unfortunately, the power is not provided, so we cannot calculate the resistance accurately. Without the power value, we cannot determine the heating time for the tea using the FeCrAl (фехраль) spiral.

Please provide the power value so that we can calculate the heating time accurately.