1. Measure the total mass of the conductor with a bench scale in meters.

2. Wrap the wire tightly around the pencil and count the number of turns n..

3. Measure the length of the wire wound on the pencil with a scale (not the amount of solution, but the amount of wire wound parallel to the pencil), which is counted as L..

Diameter of steel wire: D=L/n

Cross-sectional area S=0.25πD? =0.25π(L/n)？

M=pV=pSL total

L total =M/pS=4n？ M/pπL？