Question

Какое количество тепла выделится в нити накала электролампы за 0,5 ч,если при напряжении 120 В сила тока в цепи 2,2 А Сколько времени работал обогреватель, если при силе тока 4 А и напряжении 220 В выделилось 1,584 МДж теплоты?

Answer 1

1) Работа электрического тока превращается в тепло:
W = U*I*t = 120*2,2*(0,5*3600) =  120 *2,2 *1800 =475200 Дж.

2) Из формулы W = U*I*t  получаем t = W / U*I.
t  = 1,584*10⁶ / (4*220) =  1584000 / (4 *220) =
=1800 с = 0.5 часа.

Answer 2

Calculation of Heat Generated in an Electric Lamp Filament

To calculate the amount of heat generated in an electric lamp filament, we can use the formula:

Q = I^2 * R * t

Where: - Q is the heat generated (in joules) - I is the current flowing through the filament (in amperes) - R is the resistance of the filament (in ohms) - t is the time for which the lamp operates (in seconds)

For the first scenario, where the voltage is 120 V and the current is 2.2 A, we need to find the resistance of the filament. We can use Ohm's Law to calculate the resistance:

R = V / I

Substituting the given values:

R = 120 V / 2.2 A

Now, we can calculate the heat generated using the formula mentioned above.

For the second scenario, where the current is 4 A and the voltage is 220 V, we are given the amount of heat generated (1.584 MJ). We need to find the time for which the heater operates. Rearranging the formula, we get:

t = Q / (I^2 * R)

Substituting the given values, we can calculate the time.

Let's calculate the values step by step.

Calculation for the First Scenario:

Given: - Voltage (V) = 120 V - Current (I) = 2.2 A - Time (t) = 0.5 hours = 0.5 * 3600 seconds (since 1 hour = 3600 seconds)

To calculate the resistance (R), we can use Ohm's Law:

R = V / I

Substituting the values:

R = 120 V / 2.2 A

Now, we can calculate the heat generated (Q) using the formula:

Q = I^2 * R * t

Substituting the values:

Q = (2.2 A)^2 * R * (0.5 * 3600 s)

Calculation for the Second Scenario:

Given: - Current (I) = 4 A - Voltage (V) = 220 V - Heat generated (Q) = 1.584 MJ = 1.584 * 10^6 J

To calculate the resistance (R), we can use Ohm's Law:

R = V / I

Substituting the values:

R = 220 V / 4 A

Now, we can calculate the time (t) using the formula:

t = Q / (I^2 * R)

Substituting the values:

t = (1.584 * 10^6 J) / ((4 A)^2 * R)

Please note that we need to convert the time from seconds to hours for the final answer.

Let's calculate the values using the given formulas and the provided values.