Calculate the cross-sectional area of an 8 m long iron conductor with a resistance of 16 ohms.

Answer: 0.05mm ^ 2.
Explanation of the solution: to solve this problem, you must use the formula:
R = l * p / S, where R is resistance, R = 16 (Ohm); p – specific electrical resistance (tabular value, taken from the reference book, for iron 0.1 Ohm * mm ^ 2 / m); l – conductor length in m; S is the cross-sectional area of the conductor in mm ^ 2.
We substitute all known values into the formula:
S = l * p / R = 8 * 0.1 / 16 = 0.05 mm ^ 2.