1. (a) Compute the electrical conductivity of a 7.0-mm (0.28-in.) diameter cylindrical sil- icon specimen 57 mm (2.25 in.) long in which a current of 0.25 A passes in an axial direction. A voltage of 24 V is measured across two probes that are separated by 45 mm (1.75 in.).
(b) Compute the resistance over the entire 57 mm (2.25 in.) of the specimen.
2. An aluminum wire 10 m long must experi- ence a voltage drop of less than 1.0 V when a current of 5 A passes through it. Using the data in Table 18.1, compute the minimum diameter of the wire.
3. A plain carbon steel wire 3 mm in diameter is to offer a resistance of no more than 20 D. Using the data in Table 18.1, compute the maximum wire length.