# The electric heater consists of a nichrome coil 10 meters long and a cross-sectional area of 0.25 mm2.

The electric heater consists of a nichrome coil 10 meters long and a cross-sectional area of 0.25 mm2. What is the power of the current passing through the coil when the heater is connected to a 220V current source?

L = 10 m.

S = 0.25 mm2.

U = 220 V.

ρ = 1.1 Ohm * mm2 / m.

N -?

The power of the current N passing through the spiral is determined by the formula: N = U ^ 2 / R, where U is the voltage at the ends of the spiral, R is the resistance of the spiral.

The resistance R of a uniform cylindrical conductor with a length L and a cross-sectional area S is determined by the formula: R = ρ * L / S, where ρ is the resistivity of the substance from which the conductor is made.

We take the specific resistance of nichrome from the table of specific resistance of substances: ρ = 1.1 Ohm * mm2 / m.

N = S * U ^ 2 / ρ * L.

N = 0.25 mm2 * (220 V) ^ 2 / 1.1 Ohm * mm2 / m * 10 m = 1100 W.

Answer: the current power is N = 1100 W.

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