The resistance of the conductor R at t = 20 C is known, its length and cross-sectional area S

The resistance of the conductor R at t = 20 C is known, its length and cross-sectional area S: R = 4.2 Ohm; = 10 m; S = 1 mm. Determine the material of the conductor.

Let’s find what the specific resistance of the conductor ρ is equal to, if its resistance is 4.2 Ohm, the length l is 10 m, the cross section S is 1 mm²:
ρ = R * S / l = 4.2 * 1/10 * 1,000,000 = 4.2 / 10,000,000.
Using the reference book, we determine the material of the conductor. The closest to this value of resistivity is manganin.
Answer: the material of the conductor is manganin.