How many meters of 0.25mm fechral wire will be required to wind a 360W 120V electric motor?

To calculate the length of the spent fechral wire, we will use the equality: U ^ 2 / P = R (motor resistance) = ρ * l / S = ρ * l * 4 / (Π * d ^ 2), whence we express: l = U ^ 2 * Π * d ^ 2 / (P * ρ * 4).

Constants and variables: U – rated voltage (U = 120 V); d is the diameter of the fechral wire (d = 0.25 mm); P is the power of the electric motor (P = 360 W); ρ – electrical resistivity of fechral (ρ = 1.3 Ohm * mm2 / m).

Calculation: l = 120 ^ 2 * 3.14 * 0.25 ^ 2 / (360 * 1.3 * 4) = 1.51 m.