The current strength is 4 A at a voltage of 120 V. Find the specific resistance of the material if 18 m

The current strength is 4 A at a voltage of 120 V. Find the specific resistance of the material if 18 m of wire with a cross section of 0.24 mm2 were used for manufacturing.

Given:

I = 4 Amperes – current in the conductor;

U = 120 Volts – voltage of the electrical network;

l = 18 meters – conductor length;

s = 0.24 mm2 (square millimeters) is the specific cross-sectional area of ​​the conductor.

It is required to determine r (Ohm * mm2 / m) – the specific resistance of the material from which the conductor is made.

Find the total resistance of the conductor:

R = U / I = 120/4 = 30 ohms.

Then, to determine the resistivity, you must use the following formula:

r = R * s / l = 30 * 0.24 / 18 = 7.2 / 18 = 0.4 Ohm * mm2 / m.

Answer: the specific resistance of the conductor material is 0.4 Ohm * mm2 / m.