Question

if 18 meters of high-resistance wire with a diameter of 1.2 mm has a resistance of 10 ohms, what is resistance of 27 m of the same type of wire with a diameter of 1.5 mm?

Answer 1

The resistance is inversely proportional to the cross-sectional area of the wire and is directly proportional to the length.
If the length remains at 18 meters and the diameter is increased to 1.5 mm the resistance will become\[10\times \frac{1.2^{2}}{1.5^{2}}\ ohms\]
If the length is then inceased to 27 m the resistance will become
\[R=10\times \frac{1.2^{2}}{1.5^{2}}\times \frac{27}{18}=you\ can\ calculate\]