values In the following table.) (a) A 34.3-m length of copper wire at 20.0C has a radius of 0.23 mm. If a potential difference of 7.00 V is applied across the length of the wire, determine the current in the wire. (Use the Material Resistivity* (0 . m) Temperature Coefficient of Resistivity a [(.C)"1] Silver 1.59 x 10-8 3.8 x 10-3 Copper 1.7 x 10-8 3.9 x 10-3 Gold 2.44 x 10-8 3.4 x 10-3 Aluminum 2.82 x 10-8 3.9 x 10-3 Tungsten 5.6 x 10-8 4.5 x 10-3 Iron 10.0 x 10-8 5.0 x 10-3 Platinum 11 x 10-8 3.92 x 10-3 Lead 22 x 10-8 3.9 x 10-3 Nichrome 1.00 x 10-6 0.4 x 10-3 Carbon 3.5 x 10-5 -0.5 x 10-3 Germanium 0.46 -48 x 10-3 Silicon 2.3 x 103 -75 x 10-3 Glass 1010-1014 Hard rubber #1013 Sulfur 1015 Quartz (fused) 75 x 1016 (a) All values at 20C. All elements in this table are assumed to be free of impurities. (b) See the section "Resistance and Temperature". (c) A nickel-chromium alloy commonly used in heating elements. The resistivity of Nichrome varies with composition and ranges between 1.00 x 10-and 1.50 x 10-Q . m. 'd) The resistivity of silicon is very sensitive to purity. The value can be changed by several orders of magnitude when it is doped with other atoms. (b) If the wire is heated to 40.0*C while the 7.00-V potential difference is maintained, what is the resulting current in the wire