The heating element of an electric toaster is typically made of nichrome wire (a
ID: 1531374 • Letter: T
Question
The heating element of an electric toaster is typically made of nichrome wire (an alloy of nickel and chromium). As current passes through the wires, the wires heat up, thus toasting the toast. Estimate the overall resistance of a heating element which is 220 cm long and consists of nichrome wire with a diameter of 0.56 mm. The resistivity of nichrome is 110 times 10^-8 ohm middot m. Determine the overall resistance of a 100-meter length of 14 AWA (0.163 cm diameter) wire mode of the following materials, a. copper (resistivity = 1.67 times 108 ohm middot m) silver (resistivity = 1.59 times 10^-8 ohm middot m aluminum (resistivity = 2.65 times 10^-8 ohm middot m) iron (resistivity = 9.71 times 10^-8 ohm middot m)Explanation / Answer
Resitance is R = rho*l/A
rho is the resitivity of the material = 110*10^-8 ohm-m
l = 220 cm = 2.2 m
area of cross section is A = pi*r^2 = 3.142*(0.56*10^-3/2)^2 = 2.46*10^-7 m^2
R = rho*l/A = (110*10^-8*2.2)/(2.46*10^-7) = 9.84 ohm
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