An electric current flows through the copper wire. the length of the wire is 200 m, the voltage across it is 120V

An electric current flows through the copper wire. the length of the wire is 200 m, the voltage across it is 120V, the current strength is 1.5A. determine the cross-sectional area.

Given:
l = 200 meters – the length of the copper wire;
r = 0.017 Ohm * mm2 / m – copper resistivity;
I = 2.2 Amperes – current flowing through the wire;
U = 120 Volts – voltage at the ends of the copper wire.
It is required to determine s (mm2) – the cross-sectional area of the wire.
Let’s find the total resistance of a copper wire (according to Ohm’s law):
R = U / I;
R = 120 / 2.2 = 54.5 ohms (result has been rounded to one decimal place).
Then the cross-sectional area will be:
R = r * l / s;
s = r * l / R;
s = 0.017 * 200 / 54.5 = 3.4 / 54.5 = 0.06 mm2.
Answer: The cross-sectional area of the copper wire is 0.06 mm2.