How much wire is required?
Length of wire is L = R*A/p SI units must be used, so convert radius of 1/64in to meters: r = 0.0254 / 64 m (using 25.4mm = 1 inch) r = 3.969*10^-4 m (0.3969mm) So cross-sectional area is A = pi*(3.969*10^-4)^2 m^2 A = 4.95*10^-7 m^2 The average resistivity of nichrome is p = 1.1*10^-6 ohm-meter So the required length of wire is L = 2.2 ohm * 4.95*10^-7 m^2 / 1.1*10^-6 ohm-meter L = 0.990 m
google awg wire table and find the resistivity of nichrome wire it will have wire of different diameters listed. 1/32 is .031 or 31 mils in diameter which closely approximates 20awg wire 20awg nichrome60 wire has 659 ohms per thousand feet An example if it says 10,243 ohms/1000' you will need (2.2/10,243) * 1000 feet of wire for your resistor to Neville:--- The wire doesn't know what system of units you used to calculate the answer. It works fine in English units.
