Question

13. The resistivity of aluminum at 25 'C has been measured to be 2.72 x 10-8 0 m. The thermal coefficient of resistivity of aluminum at 0 C is 4.29 x 10-3 K-1. Aluminum has a valency of 3, a density of 2.70 g cm3, and an atomic mass of 27 a. Calculate the resistivity of aluminum at-40°С. (Ans: 2.03 x 103 Ω m) b. What is the thermal coefficient of resistivity at-40'C? (Ans: 5.23x 103K c. Estimate the mean free time between collisions for the conduction electrons in aluminum at 25 *c, and hence estimate their drift mobility. (Ans: 1.27 x 103 m/Vs) d. If the mean speed of the conduction electrons is ~1.5 x 106 m s-1, calculate the mean free path and compare this with the interatomic separation in Al (Al is FCC). What should be the thickness of an Al film that is deposited on an IC chip such that its resistivity is the same as that of bulk Al? (Ans: 10.8 nm) e. What is the percentage change in the power loss due to Joule heating of the aluminum wire when the temperature drops from 25 iC to-40 "C? (Ans:-25.4%)

Answer 1

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