Here is a round pencil and a scale with division value of 1 mm. How to measure the diameter of the thin copper wire

Here is a round pencil and a scale with division value of 1 mm. How to measure the diameter of the thin copper wire

Wrap the copper wire tightly on the pencil for several turns (the more turns, the better the accuracy). Measure the length of several turns on the pencil. Divide the length by the number of turns to get the diameter of the copper wire

Two pencils of the same diameter, a copper wire of known diameter, please try to measure the diameter of another coil of copper wire!
Be specific

Use copper wire with known diameter to wind a pencil, and record the number of winding a
When winding another pencil with another roll of copper wire, when the width of winding is the same as that of the previous one, count the winding times B
If the diameter of known copper wire is d
Then the diameter of copper wire with unknown diameter is a * D / b

There are two identical pencils, one coil of copper wire with known diameter. Please try to measure the diameter of another coil of thin copper wire

The pencil is wound around the pencil, and then the pencil length is divided by the number of turns of the thin copper wire