Question

3. чему равно напряжение на концах провода, если по железному проводу длиной 150 м, площадью поперечного сечения 0,025 мм2 проходит ток 250 мА? .

Answer 1

Ответ:

U = 150 B.

Объяснение:

Дано:

L = 150 м

S = 0.025 мм²

I = 250 мА = 0,25 А

ρ = 0,1 Ом·мм²/м - удельное сопротивление железа

Найти:

U - напряжение

Решение:

Сопротивление провода

$R = \rho \cdot \dfrac{L}{S}$

Напряжение в соответствии с законом Ома

U = I · R

$U = \dfrac{I\cdot \rho \cdot L}{S} = \dfrac{0.25\cdot 0.1 \cdot 150}{0.025} = 150~(V).$

Answer 2

Calculation of Voltage

To calculate the voltage drop across the iron wire, we can use the formula:

Voltage (V) = Current (I) × Resistance (R)

The resistance of the wire can be calculated using the formula:

Resistance (R) = (ρ × L) / A

Where: - ρ is the resistivity of iron (ρ = 9.71 × 10^-8 Ωm) - L is the length of the wire (150 m) - A is the cross-sectional area of the wire (0.025 mm^2)

Let's calculate the resistance first.

Calculating Resistance

Using the formula for resistance:

Resistance (R) = (ρ × L) / A

Substitute the given values: - ρ = 9.71 × 10^-8 Ωm - L = 150 m - A = 0.025 mm^2 (convert to m^2 by dividing by 10^6)

Resistance (R) = (9.71 × 10^-8 × 150) / (0.025 × 10^-6)

Resistance (R) = 0.0005786 Ω

Calculating Voltage

Now, using the formula for voltage:

Voltage (V) = Current (I) × Resistance (R)

Substitute the given current: - Current (I) = 250 mA (convert to A by dividing by 1000)

Voltage (V) = 0.25 A × 0.0005786 Ω

Voltage (V) = 0.00014465 V

So, the voltage drop across the iron wire is approximately 0.00014465 volts.