Level 1: Why Are Heater Coils Nichrome, Not Copper?
How long is the coil?
A 1000 W, 220 V heater coil is made of nichrome wire of resistivity 1.1 × 10⁻⁶ Ω m and cross-sectional area 0.1 mm². The length of wire needed is about:
First find the resistance the coil must have from its rating, then use R = ρL/A. Remember to convert the area: 0.1 mm² is 1 × 10⁻⁷ m².
About 4.4 m of nichrome wire is needed, which fits in a small coiled element. The same resistance in copper wire of this thickness would need almost 300 m of wire.
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