The resistance of a copper wire increases if it is heated and decreases if it is cooled. What will happen to a circuit made of copper wire if the temperature drops from 40°C to 20°C?
A.The current, voltage, and resistance will all increase.
B.The voltage and the resistance will remain constant.
C.The current will increase and the resistance will decrease.
D.The resistance will increase and the voltage will remain constant.
I'd say the answer was C. Wire cools, so resistance decreases. Low resistance mean higher current. One possibly spectacular example of this is SUPERCONDUCTIVITY, much used in persistent current carrying coils in hospital imaging equipment, I think.
