Copper has positive temperature coefficient; light bulb gets brighter when copper leads are dipped in liquid N2.
What it shows:
Copper has a positive temperature coefficient (≈ 3.9×10-3 per ˚C), which means that its resistance drops with temperature. Here copper wire is immersed in liquid nitrogen (77˚K = -196˚C), decreasing its resistance (from room temperature) by almost a factor of 2, thus increasing the current flow though a circuit.
How it works:
We have a coil of 30AWG copper wire...
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