Spiral of an iron with a power of 1 kW made of wire with a cross section of 0.1 millimeter square.

Spiral of an iron with a power of 1 kW made of wire with a cross section of 0.1 millimeter square. The iron is plugged into a 220V network. Determine the length of the wire.

Initial data: P (power of the iron spiral) = 1 kW = 1000 W; U (effective voltage in the network) = 220 V; S (spiral cross-sectional area) = 0.1 mm ^ 2.

Constants: the spiral is made of nichrome or fechral wire, ρ (nichrome resistivity) = 1.1 Ohm * mm ^ 2 / m.

1) Resistance of the spiral: P = U ^ 2 / R; R = U ^ 2 / P = 220 ^ 2/1000 = 48.4 ohms.

2) Wire length: R = ρ * l / S; l = R * S / ρ = 48.4 * 0.1 / 1.1 = 4.4 m.

Answer: The length of the nichrome wire is 4.4 m.