I need to build a resistor that will serve as a heat source to test the performance of a Peltier cell.
I want the resistor to have a square plate geometry, of 40 mm × 40 mm and a height the shorter the better. The length and width can grow a bit. However, I am having trouble selecting the material I should use.
I can use power sources preferably of 12 V or 120 V, and I want the resistor to dissipate between 5 W and 10 W. The solution of the resistance estimation equation $$R = \rho \frac{L}{A}$$ yields that I need a material of resistivity between 0,14 Ωm and 0,30 Ωm if I use a source of 12 V and between 14 Ωm and 30 Ωm for a 120 V source.
How would you go about this? I was thinking of using salt water but its resistance is said to vary highly with temperature.