Question

Десять параллельно соединенных ламп по 0,5 кОм, рассчитанных каждая на напряжение 120 В, питаются через реостат от сети с напряжением 220 В. Какова мощность реостата? Какой длины нихромовый провод сечением 0,5 мм² пошел на изготовление этого реостата? Помогите срочно решить эту задачу!!!С ДАНО И РЕШЕНИЕМ УМОЛЯЮ ПРОСТООООО

Answer 1

Дано: n = 10, R1=0,5 кОм= 500 Ом, U1 = 120 B, U = 220 B Найти Р.

Решение.
На скрине

Ответ: Р = 240 Вт.
По длине провода не знаю

Answer 2

Problem Analysis

We are given a circuit with ten lamps connected in parallel, each with a resistance of 0.5 kΩ and designed for a voltage of 120 V. These lamps are powered through a rheostat from a power supply with a voltage of 220 V. We need to find the power rating of the rheostat and the length of the nichrome wire used to make the rheostat.

Solution

To find the power rating of the rheostat, we can use the formula:

Power (P) = Voltage (V)² / Resistance (R)

Since the lamps are connected in parallel, the total resistance of the circuit is the reciprocal of the sum of the reciprocals of the individual resistances:

Total Resistance (R_total) = 1 / (1/R1 + 1/R2 + ... + 1/Rn)

where R1, R2, ..., Rn are the resistances of the individual lamps.

To find the length of the nichrome wire used to make the rheostat, we need to know the resistivity of the nichrome wire and the cross-sectional area of the wire. With this information, we can use the formula:

Resistance (R) = Resistivity (ρ) * Length (L) / Cross-sectional Area (A)

Let's calculate the power rating of the rheostat and the length of the nichrome wire step by step.

Calculation

1. Power rating of the rheostat: - The voltage across the lamps is 120 V. - The voltage supplied by the power supply is 220 V. - The power rating of the rheostat can be calculated using the formula: P = V² / R_total. - Let's calculate the total resistance of the circuit first: - The resistance of each lamp is 0.5 kΩ (0.5 * 10^3 Ω). - The total resistance can be calculated as: R_total = 1 / (1/R1 + 1/R2 + ... + 1/Rn). - Substituting the values, we get: R_total = 1 / (1/0.5 * 10^3 + 1/0.5 * 10^3 + ... + 1/0.5 * 10^3). - Now, let's calculate the power rating of the rheostat using the formula: P = V² / R_total.

2. Length of the nichrome wire: - We are given the cross-sectional area of the nichrome wire as 0.5 mm². - We need to know the resistivity of the nichrome wire to calculate the length. - Unfortunately, the resistivity of the nichrome wire is not provided in the given information. - Without the resistivity value, we cannot calculate the length of the nichrome wire accurately.

Answer

Based on the given information, we can calculate the power rating of the rheostat using the formula P = V² / R_total. However, we cannot calculate the length of the nichrome wire without knowing the resistivity of the wire. Please provide the resistivity value of the nichrome wire to accurately calculate the length.