Determine the resistivity of a conductor 42 cm long and 0.7 mm in diameter at a current strength of 0.5 A and a voltage of 0.6 V.

L = 42cm = 0.42m.

d = 0.7 mm = 7 * 10^-4 m.

I = 0.5 A.

U = 0.6 V.

ρ -?

The resistance R of a cylindrical homogeneous conductor is determined by the formula: R = ρ * L / S, where ρ is the resistivity of the material from which the conductor is made, L is the length of the conductor, S is the cross-sectional area of ​​the conductor.

We express the resistance of the conductor R according to Ohm’s law for the section of the circuit: R = U / I, where U is the voltage at the ends of the conductor, I is the current in the conductor.

ρ * L / S = U / I.

ρ = U * S / I * L.

The cross-sectional area of ​​a cylindrical conductor S is expressed by the formula: S = P * d ^ 2/4.

ρ = U * P * d ^ 2/4 * I * L.

ρ = 0.6 V * 3.14 * (7 * 10-4 m) ^ 2/4 * 0.5 A * 0.42 m = 1 * 10 ^ -6 Ohm * m.

Answer: the resistivity of the conductor is ρ = 1 * 10 ^ -6 Ohm * m.