Current and Resistance9317.57The current in the wire is 15.0 V150 A0.100 VRI∆===ΩThen, from dvInq=()A, the density of free electrons is ()()22419150 A3.1710m s1.6010C5.0010mdInverπ−−×××3−or 2833.7710mn=×17.58At temperature T, the resistance of the carbon wire is ( )001cccRRTTα=+−, and that of the nichrome wire is ( )01nnn0. When the wires are connected end to end, the total resistance is ( )( )0T00c ncnRRRαα+++kcnRR RRT=+=−If this is to have a constant value of 10.0Ωas the temperature changes, it is necessary that (1) and 10.0 k+=0Ω+10.0k0.4Ω−=10.0 k=Ω−0.5010 CR−×°+(2) From equation (1), , and substituting into equation (2) gives
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