For some material the resistivity drops to near-zero below a certain temperature (the critical temperature) For such a material, current would continue to flow even if the potential is zero! A person replaces a cable with R=10 Ohm with one that is twice longer to increase the resistance. The cable has a temperature coefficient of resistivity of 4x10-3 1/K. Instead of making the cable longer, he could have raised its temperature by what value?