Question

A wire has a resistance of 27.2 ohms. It is melted down, and from the same volume of metal a new wire is made that is 3 times longer than the original wire. What is the resistance of the new wire?

Resistance and length of wire are proportional, but what I am unsure of is if the width has to be factored in, if so, I have no idea how to do so. As you increase the length from the same volume, the width would decrease. If you don't factor this in, it's just (27.2)(3)= 81.6 ohms. Please help!

Answer 1

If it is three times longer, it must have 1/3 the cross sectional area of the original wire. The new resistance will be nine times higher.