Given,
Number of turns (n)=820
Length of the coil (l)=9inch=0.0254×9m=0.2286m
Diameter of the wire (d)=32mils=32×2.54×10−5m=81.28×10−5m
Let total resistance of the coil =(R)
We know that the resistivity of the annealed copper at 20oC(ρ)=1.72×10−8Ωm
Cross sectional area of the wire (A)=4πd2m2=43.14×(81.28×10−5)2=5.18×10−7m2
We know that,
Resistance of the coil (R)=Anρl
Now, substituting the values,
⇒R=5.18×10−7820×1.72×10−8×0.2286Ω
⇒R=6.2Ω
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