Question

A single layer of No. 24 AWG (dia=0.0201 in) commercial iron wire is wound over a ceramic tube whose diameter is 3.25 in. if the total wire resistance is 41 ohms, determine the number of turns.

Answer 1

Solution

Given data

Diameter (d)=0.0201 in

Resistance (R)=41$\Omega$

Circumference of ceramic tube(c)$=\pi D$

=$\pi\frac{3.25}{12}=0.85ft$ =1turn

And CM=$\frac{0.021}{0.001}=404.01mil^2$

Resistance

$R=\rho \frac{L}{CM}$

$L=R\frac{CM}{\rho}=\frac{41\times404.01}{75}=221ft$

No. of turns

$N=\frac{L}{C}=\frac{221}{0.85}=259.83$

$N=260$

Therefore number of turns are 260.