Question

A wire of resistance 16 ohms is elongated to double its length. What is the new resistance?

Answer 1

the resistance will be doubled

Answer 2

Since R is proportional to length and inversely proportional to area (or R^2), doubling the length doubles the resistance, and half's the cross sectional area—so the resistance of the long wire is 2 x 2 =4 times the original resistance (16 Ohm), so the new resistance is 4x16=64 Ohms.