https://en.wikipedia.org/wiki/Constantan
>"Its main feature is the low thermal variation of
its resistivity, which is constant over a wide range of temperatures."
In other words, NOT a square relationship nor even a linear one(!) -- in the temperature range where Constantan's resistivity is constant...
(At least, according to Wikipedia...)
https://en.wikipedia.org/wiki/Constantan
>"Its main feature is the low thermal variation of
its resistivity, which is constant over a wide range of temperatures."
In other words, NOT a square relationship nor even a linear one(!) -- in the temperature range where Constantan's resistivity is constant...
(At least, according to Wikipedia...)