Question

Требуется изготовить реостат на 20 Ом из никелиновой проволки площадью сечения 3мм"(в кадрате). какой длины проволка потребуется для этого? Удельное электрическое сопротивление никелина 0,4 Ом"(в квадрате) /м

Answer 1

Решение:
R=pl/S
L=0,4*3/0,087=13,8 метров

Answer 2

Calculating the Length of Nickel-Chromium Wire for a 20 Ohm Resistor

To calculate the length of nickel-chromium wire needed to create a 20 Ohm resistor, we can use the formula:

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

Where: - R = Resistance (20 Ohms) - ρ = Resistivity of nickel-chromium wire (0.4 Ohm * mm^2 / m) - L = Length of the wire (to be calculated) - A = Cross-sectional area of the wire (3 mm^2)

Calculation

Using the formula, we can rearrange it to solve for the length (L):

L = R * A / ρ

Substituting the given values: L = 20 Ohms * 3 mm^2 / 0.4 Ohm * mm^2 / m

Result

Calculating the length of the wire: L = 150 mm

Therefore, the length of nickel-chromium wire required to create a 20 Ohm resistor with a cross-sectional area of 3 mm^2 is 150 mm.